I purchased Telerik controls after spending some time using the demos and trial. However, I did not work very far into the advanced features before purchasing.

It turns out that there is almost zero documentation for anything but the most basic of functions, the controls have major bugs which go unfixed for years, and the support staff is unable to understand most questions.

What was to be a 3 month project has just hit 6 months, and I put the blame for that squarely on Telerik. Out of any given day, I spend almost 6 hours trying to find information on how to work around their controls, or get them to work at all. 

If you are evaluating Telerik, I advise you to search around the web for complaints about them. You will find that there are many, and that they all have a common complaint of poor documentation and bug-ridden controls. 

http://www.gitshah.com/2011/03/telerik-controls-perfect-example-of-how.html

http://www.telerik.com/forums/poor-documentation

Hello,

As we have already discussed, we do offer an extremely wide range of controls and features and we do our best to provide proper documentation for each of the controls and features we offer. Still, there might be gaps and we are grateful when our users are reporting them. 

At the same time, we strive to offer one of the best support services on the market and we always encourage our clients to contact us when there is something they need with our components. With that said, I do not see many inquiries from your side. We do want to help you with your project and we will do our best to make your live easier by using our components. Still, if you feel that our suite or the services that we offer (support and documentation) do not cover your needs, you can contact our sales department at sales@telerik.com and ask for a refund.

Alternatively, if you decide to continue using our products, we will be glad to continue addressing your questions.

Regards,
Stefan
Telerik

Stefan,

You said: "Still, there might be gaps and we are grateful when our users are reporting them. "
I would disagree, since I've been giving specific examples of documentation missing for months now, yet I have not seen any improvement. Furthermore, I've run across forum posts making the same exact suggestions I have, as far back as 2009. If you haven't fixed the gaps in 5 years, I would say you are not entirely interested in having us report them.

You said: "I do not see many inquiries from your side"
I have submitted over 14 tickets, several forum posts, and an ongoing series of emails, all in only 3 months of using the product. I was told in a support ticket that I should expect to submit up to 3 tickets per week. That means I am stopped from completing a task for up to 24 hours 3 times per week. If experienced developers need to ask that many questions, something is wrong.

You said: "you can contact our sales department at sales@telerik.com and ask for a refund. "
Apparently, no, I cannot. I tried and was told there are no refunds..

For others seeing this thread, here's a few examples of what I'm talking about:

http://www.telerik.com/forums/telerik-advanced-search   -2009    Fixing the Forum
Search – Still not done, I made the same suggestions before finding this post.

http://www.telerik.com/forums/poor-documentation   - 2011  Documentation concerns from
multiple people.  No answers, someone else derailed the thread.

http://www.gitshah.com/2011/03/telerik-controls-perfect-example-of-how.html  - 2011   Look at the multitude of
comments on this article.

http://www.telerik.com/forums/documentation-usage  - 2012   Same complaints about
documentation. Same promises. Nothing has changed.

http://markfreedman.com/index.php/2011/08/09/wrestling-with-the-telerik-mvc-grid-control-part-1/ - 2014  See the last comment. The author was a fan, but it seems he’s also been burned by the poor documentation.

Hello Jeff,

It was my understanding that you were mainly talking about the WinForms product, which does not seem to be the case, given the links provided. Although I would not argue with you, you can still see our point of view further in my reply.

In regards to the support ticketing system and the 24-hour turnaround time, you are correct that you may be prevented from continuing working on a specific task at this time. Therefore, we are striving to cover not only articles covering the features and API of the components, but also scenarios that can be achieved with these features. Not every single scenario may be covered and we are updating the documentation with the input that we get from our customers. Note also, that you may ask questions while prototyping your application checking if Telerik products would serve your application needs even during your Trial period of 30 days.

As to the WinForms documentation improvements in particular that you regarded in your support threads, they are scheduled, still there are other tasks to be implemented in the documentation beforehand.

In regards to the links that you provided, I would point out that they are old threads and for a great range of products. While we do our best to make all our customers happy, there could be single cases like these where for some reason one may not be satisfied with a particular product/documentation for a particular purpose. Moreover, in most of the cases things have progressed in a positive direction. 

http://www.telerik.com/forums/telerik-advanced-search   -2009    Fixing the Forum
Search – Still not done, I made the same suggestions before finding this post.
We have already improved our search capability of the website with the latest release of the website (mid-January). While we have implemented improvements on the back end, we continue to take in feedback around our search to see what we can do to make it better. Directly concerning the answer of Atanas, the fact that something is logged in our bug tracking system, and despite our good will, does not necessarily mean that it will be implemented in the next release. We are trying to consolidate the customer requests and pick those that are voted most, which would bring value to the largest group of users. At the same time, it is not only the number of voters, but the exact feature specifics wanted that would serve all, so that we can shape the feature best.

http://www.telerik.com/forums/poor-documentation   - 2011  Documentation concerns from
multiple people.  No answers, someone else derailed the thread. 
Here, you are correct that the thread was derailed. Regarding the documentation itself, in 2011 Kendo UI was pretty new product in the Telerik portfolio and its documentation has been highly improved since then. Even then, however, despite the lack of documentation there were video tutorials on the topics asked by Krzysztof. To support my words about the improved documentation, you can find a sample DataSource Model definition in this section of the API reference documentation. As to Column formats - you can refer to this topic from the API documentation which illustrates what formats are applicable for grid columns, including a short example. We do not offer offline version of the documentation, and we update it frequently online to be able to reference the latest version at any point in time at docs.telerik.com/kendo-ui.  
http://www.gitshah.com/2011/03/telerik-controls-perfect-example-of-how.html  - 2011   Look at the multitude of comments on this article. 
While it does pain us to see that a few of the comments mention the Telerik products in a negative way, we are aware that sometimes the approach we take to building our controls does not always fit the schema to what other developers are used to, or expect. As you can imagine, one scenario that might be the most apparent to one developer and requires a certain amount of features to be implemented may make sense to him or her, but when it comes to another developer they might have completely different requirements. Given the same requirements two developers would most likely take two different routes to reach the same goal, and might not agree with the other developer’s approach upon checking each other’s code. What we’ve tried to do with our controls is make them as extensible as possible to try to ensure that we can cover all of our clients scenarios. This has led to success in most for most of our clients, but sometimes people cannot see past that the controls do something in a way that they think is illogical since it is not the way they would have implemented it.

Most of the time our online resources (demos, documentation, code libraries, etc.) alongside with support solves all the issues that our clients run in to. The times it does not we’ve actually implemented fixes or features in our controls for a future release.

That being said, there are times when this does not work out or someone had one bad experience that left them with a sour taste in their mouth. Finding a blog post and commenting on it may be their source to vent these frustrations. However, any feedback that we find, even if it is negative, we use as a way to push our resources further. If we find any piece of information that we can use in comments like these we will be sure to add it to our backlog of issues to resolve for upcoming releases. http://www.telerik.com/forums/documentation-usage  - 2012   Same complaints about
documentation. Same promises. Nothing has changed.
The article from the chart documentation has been updated to reflect the format options and references the kendo.format method as well. We appreciate the feedback we incrementally include updates and expand the existing documentation.

http://markfreedman.com/index.php/2011/08/09/wrestling-with-the-telerik-mvc-grid-control-part-1/ - 2014 See the last comment. The author was a fan, but it seems he’s also been burned by the poor documentation.
This info relates to our MVC grid from the discontinued Telerik MVC Extensions product. A Telerik member responded in the comments of the blog, that guy should check our Kendo UI MVC grid counterpart and provide feedback. 

Regards,
Nikolay
Telerik

Nikolay,

I was using WinForms products during my experience. However, I have pulled these examples out from various areas to show an established pattern of disregard for proper documentation, quality assurance and patterns/practices across all Telerik products.

Not every single scenario needs to be covered by the documentation, but all functionality designed into the controls should be covered. I should be able to find how to retrieve and append text from your RichTextBox document object in your documentation. I should be able to find out the difference between your RadTextBox and RadTextBoxControl from your documentation.

Thank you for pointing out the age of the threads I provided.  I purposely referenced a range of posts from 2009 to present to show how this is a consistent pattern with Telerik and how the regular promises to improve are never actually realized.

If you have improved your search capability then why do I still have results from 2009 and prior coming up in the top 10 results for some searches? Where are the keywords, date-ranges, subject search, answered vs not-answered search? I've yet to run across another developer forum that does not have these basic features.
http://www.telerik.com/forums/searching-and-getting-results#PWug-0YwekinZJ4uIZLefg

"sometimes people cannot see past that the controls do something in a way that they think is illogical"
Like the GridView RowValidating event which is fired after the unvalidated row/data is committed to the datasource with no way to roll back? Yea, I do have a problem seeing past that.

Given the length of your response, it seems Telerik does take reputation seriously. If that is the case, then your time would be better spent improving your product.

I happen to agree with Jeff wholeheartedly! The forums are not the place to correct documentation issues, they need to be found and fixed in the documentation, You should NEVER rely on your customers to correct your information, you should have someone that is a non-developer, developer trying to make each of your demos work, and then TESTING oddball and edge cases to be sure that you at the very least have a work around or note in the demo about things that do not work as expected, with the sheer volume of tool sets you have, if you do not have a minimum of a 10 man team working on demo code and documentation testing and quality control you are simply failing in your commitment to your customers, working through each of his points and providing EXCUSES for poor quality show a serious lack of professionalism and acceptance of accountability on Telerik's behalf.

I think overall the documentation is fair. I definitely experienced a slowness in development when I started using some of the Telerik controls for the first time. There is a learning curve. I've used them for a few years now so I have a much better idea of how to approach issues. Having said that I do wait 1-2 days for reply's to issues or sticky points in the code where things are not working out as I would think they would.  I do feel that the examples Telerik gives are most often the most basic of scenarios. When coding in the "real" world you know that these scenarios are not the norm. 

I would rate Telerik overall with support and documentation around a 7 out of 10. They have a lot of controls and its not easy to keep it up to date when you consider how aggressively they roll out new products.

The controls themselves are pretty good. Not sure when ASP.NET 5 and Windows 10 are out however if I don't move to another platform altogether.