Agreed that it is not snappy enough. It's far from it, flicking between programs using either Alt+Tab or Winkey+Tab, scrolling on web pages...just feels very far from being optimised. I'm running on a v. good processor, 1gb ram and nvidia quadro card.
Vista itself has not crashed and feels solid that way. But some of the programs I have run on it crash when using, for example, the standard File-Open dialog box; it just crashes the program and I cannot find a way to resolve it except to restart Windows. Hopefully compatibilities will be further improved by its release but I don't know.