I don't have many bug related issues - but the few I have are annoying and give me the impression that Vista is still immature and/or developers are slacking it.
I'm mostly disappointed by the lack of 64 bit apps - sure, you can have more applications running if you have enough RAM, but I'm more interested (and I believe most would be as well) in being able to do more in the individual apps such as 2D, 3D and video related work.