The major problems with Vista are not found in Windows itself but rather the support for hardwares. The latest vdeo and sound cards are seeing fun there. The most common complaint is one that many fail to take into account mainly it's a larger OS over XP with new features seeing more startup items lke the Aero Style resource grabber there.
Vista does actually run more stable while lacking some of the old features like the add/remove Windows components option found in the add/remove section in all previous versions back to 95! You're stuck with what it comes with without any items you can download separently. Direct X is no longer a separate item but comes included in Windows like WMP 11 and IE 7. Will IE 8 and WMP 12 be availble for Vista?
Each version does have some minor bugs to work out. XP had it's own while now seeing it's best with SP3 coming out when???ever... The gamers who first tried the beta releases and were expecting big results fooled themselves expecting any there. Beta means "for evaluation only". Vista is now taking in the amount of hardware changes seen in the last several years and naturally uses a little more memory by default.