I have been using vista since rc1. it has had is fair share of problems. I also have been using xp since RC2. and i had more issues with xp then i have had with vista. The biggest problem i have run into with vista is it's hardware requirements, wich was also an issue with xp, but not quite as bad. Other then that vista has been rock solid for me, both x86 and x64. If it wernt for the hardware i would have upgraded our systems here at work. The benifits i would gain from upgrading at work is not worth the cost at this point, But at home i have vista on all but 3 of 11 pcs, and couldnt be happier.
thats my opinion.