Sorry, but that's also FUD. I used Vista 64 from Beta 2 when it was very buggy, but starting with RC2 it was not. There were problems with older hardware, but not with the latest generation. Used with newer hardware and 2GB of RAM it ran very smoothly and, in my case, much better than XP.
The problem was in addition to the older hardware that Superfetch took a few days to speed up the system, but by then many had already given up and called Vista garbage. Add to that the indexing that made the harddrive spin almost constantly in the first few days and the terrible marketing from MS. And lets not forget that much of the UI changed which made many users mad.
SL was smart to avoid the UI changes with SL, but as we see the changes in architecture are already angering many like in this thread.