Most hyped Software Product released, with 6bn$ investment and over 5years in development - Finally Windows Vista is here. Now, Microsoft marketing blitz for Windows Vista has begun. Confusion and temptation of when to buying Vista?? is question of the season.
If you want a truly seamless transition to Vista - especially if you're upgrading your existing PC versus buying a new one with it pre-installed - I'd say wait. Not the possible 11 months or so it will take for Service Pack 1 to come out, but maybe a month or two to let software and hardware vendors to work out the kinks with their apps and drivers.
Also, Vista haven't publish kernel OS code for 3rd Third party tools/software. So you will not find any 3rd party software for Vista as of yet.
Its good to remember - Historically Microsoft releases a really shoddy product on its initial launch. Windows 95, Windows 98, Windows ME (never had a shining moment anyway), and Windows XP were all mediocre or even terrible until the first or even second service pack or equivalent, with the exception of ME which was just plain terrible.
Vista already has known issues with lots of common hardware. It also doesn't seem to have *really compelling* features to drive an upgrade. And of course, the biggest reason to not upgrade now, is the COST.