Vista's biggest (and IMO, only) problem is the huge decrease in performance from XP. If you're a gamer, DirectX 10 can mitigate some of that, as can the increase in support for 64bit compatibility that Vista ushered in (64bit = more ram = potentially better performance), but it's still disappointing that Vista is so sluggish by comparison.
The good news is that, even with some of the new features in Windows 7 (I really love the new task bar and aero peak, for example), it's supposedly outperforming Vista at the same time in a variety of benchmarks. I see the switch from XP->Vista->Win7 as an analog more to the switch from 3.1->95->98. 3.1 was stable and fast and well supported at the time. Windows 95 was buggy, and the performance was poor, and since the major change was largely cosmetic, I know a lot of people who skipped 95 altogether. 98 was essentially a reskin of 95, but it did a lot of things better and went on to be one of the more stable and long lived OSes in MS' history. Only time will tell if Win7 follows in it's footsteps.