Just a couple of points. Both x-64 bit versions.
Windows 7 build 7077 -- 100% OK
Windows 7 build 7100 -- few glitches
1) install had to uninstall some pre-existing drivers
on "Upgrade" before it would install -- and you've guessed it -- couldn't re-install the drivers again.
On "New install" drivers wouldn't install in any way --even in compatability mode.
2) some 3rd party apps ran fine in build 7077 but "Crap out" in 7100.
3) .NET is 100% totally hosed and bollixed up in 7100 -- hopefully this will be fixed by RTM. Cannot install ANY .Net 2.0 apps -- worked fine in 7077.
4) 3rd party TV application doesn't run AT all in 7100 -- I NEED this for viewing composite video -- WMC is fine for normal TV viewing
Performance wise both builds seem OK.
However if this is RC it seems a couple of steps backwards from build 7077 as far as installability and compatability are concerned.
I'll leave it for a little while longer but my gut feel currently is to revert back to build 7077 until some fixes or "Service packs" come out.