I just updated my Visual Studio 2012 RC to RTM and this is my experience with it.
- I had 2012 Ultimate RC so I had to uninstall it before installing the VS 2012 Premium. (not sure about upgrade from RC to RTM)
- Team Foundation Server (TFS) was already configured in the Ultimate and after the uninstall and install it was picking the TFS config automatically.
- It took me about 2hrs to do the entire process of uninstall and install.
- I'm running it and didn't encounter any problems so far.
Good Job guys!