I have been running Vista for 3 months now, admittedly on quite a powerful machine (Dell XPS Quad Core).
In the early days I was considering throwing it away and putting XP on the box, 3 months in and having got round the UAC niggle (which is not actually a bad idea if you consider the rationale behind it) I'm quite happy to keep Vista.
There is nothing I have tried to do with it that I have not been able to in terms of software or peripherals although I believe this has not been the universal experience.