It's not a bad OS
I've been running Windows 7x64 since about 2 days after the final retail was released on the internet.
The one and only problem I have had so far is the Windows desktop being a bit buggy, a few times the desktop appeared to stop updating itself, so if you copied something there or deleted something the icons didn't appear/disappear on screen. Oddly enough I had the exact same problem on Vista obviously a bug they don't know about but easily fixed by refreshing the desktop although not fixed until you rerun explorer.
I had trouble finding Win7 specific drivers, but is to be expected as it was not officially released at the time. Windows Vista drivers worked fine for the most part (except the audio driver which seemed to batter the CPU) but to be fair it did have a Microsoft driver that I used instead until a few weeks later a proper Windows 7 driver was released.
I can't think of any other problem that are not fixed by running apps in compatibility mode which I have had to do a few times (same on Vista). I still have turned off UAC though, as it is as annoying as hell stopping certain apps from worked properly, and their policy of signed drivers only kind of irritates me a bit, same on Vista though.
It's a good desktop OS but in my opinion should have been a fix for Vista. Bug fixing and optimisation should not be a pay for item in my opinion. Linux is still the better OS for networking and serving though as windows networking sucks big time, but that's to be expected.