I installed it last night. Honestly, other than a few UI changes, it isn't any different than 7048. There is a bug with a desktop.ini file launching everytime windows starts up. There is a fix out there for it:
I run x64 on all my main machines, but x86 on a laptop. Again, other than some small UI changes, there isn't much different. One thing I did notice is when you disable UAC, you now receive a prompt. This was supposed to have been fixed in previous builds, but this is the first build I have seen it functioning properly. Before you could disable UAC without being prompted and confirming. I hope for the RC they manage to get all of the icons changed to the newer style. The vista style icons and the windows 7 style icons don't go well together.