The most commonly reported/voted for Connect bugs in the Release candidate had to do with the ASP.NET designer not auto generating controls properly - it would sometimes just omit them.  Very frustrating if you are trying to use it.  We've just release a patch (the 3rd RC patch in total) to address this set of issues.  You can read more about the patch here:

And you can download and install it here:

Hopefully this will address this issue and get you moving forward again.