Thank you for your feedback. We know that PDF, Docx are the mostly used formats these days.
Unfortunately the Silverlight runtime do not contain anything to help us render them. As you mentioned there should be a separate tool to convert those formats to XAML. Writing such tool is not impossible but surely hard and with data loss. Such tool however is not part from the Book control. As it is a SL control it should rely on XAML to render its content.
What we are doing right now is to enable easier integration with images so you can easily create scenarios like photo albums, online magazines, etc ...
Hopefully as the platform emerge there will be tools that will enables us render richer formats, like the ones you mentioned.
As for the help articles - I can assure you that we are working very hard on this. The first results are already online. The controls that receive a much needed help refreshments are the Grid
. We are now working on better help for RibbonBar and ComboBox. If you have any feedback on the help articles for the Grid, Tree or Chart - please let us know.
We are also working on a courseware for Silverlight that is ~1000 pages long, like the one we have for our Ajax controls - http://www.telerik.com/support/documentation-and-tutorials/step-by-step-tutorial-for-ajax.aspx
the Telerik team