I shudder to think what it was like in Vista if you think it isn't that bad in win7. On my netbook with win7 and UAC set on the lowest level I think it is the devils spawn.
I frequently wanted to know just whose computer it was mine or UAC. I absolutely hated its total lack of configurability as it constantly block the same application time after time after time.
In the end I gave up and completely disabled it, a right pain in the rear.