The only real problem I've hit so far (installed a couple weeks ago) is that my phone doesn't get recognized on ONE of the machines (I have it now installed on two machines) -- on the other one it was recognized/working fine. Hopefully I'll figure it out, maybe need a reboot or something...
The other thing is that the 64-bit version doesn't seem to support hardware acceleration for VM (virtual machines), so the VM I'm running on it is now actually slower than it was on Vista, but if you're installing 32-bit and/or don't care about VMs, then this is not an issue for you.
One other small gripe, there is no way to configure "classic" style for start menu (not the button, but the menu itself); you could still do it in Vista, but not anymore. Getting used to it, nothing deadly.
All in all, -- it's alright. I don't understand why all the hype (though I'm working off of a desktop with a lot of memory and good speed, and I hear it really shines in laptops, so maybe that's why people are raving?) but it's nice/ok. Solid so far.