Thank you for the interest in the web viewer.
As of today we have a few issues that prevent us from releasing the MVC report viewer to the public. The Q2 2013 release is in a week and there is a high chance that we will reschedule the release of the report viewer for later (SP1).
Anyway the Q2 2013 release is a major milestone for Telerik Reporting as we are switching to .NET 4; we are also preparing a plenty of new features and improvements of the Graph item.
Have you tried the new visualization options in Telerik Reporting Q1 2013? You can get them from your account.