Seems to be ok for me, not run any benches though.
One thing I've noticed is that they are making my GTX280 flip between 2D and 3D mode on the desktop while not doing anything. Seems to be triggered by aero because when its turned off it stops.
There are a few posters over at the guru3d forum getting the same issue, thing is I used to get that on Vista64 SP1 and a couple of the 18x.xx drivers but SP2 sorted that for me, and I can adjust my fan speeds just fine on the 9500GT so tomorrow I'll have to see how the 8800GT's get on with it.
Thats most likely the case, at least for ATI, as they need those new drivers for their new cards, this may be a good sign for nVidia buyers, in an offbeat way