Vista is a strange beast, touted as the next big thing by Microsoft (MS) and much scorn from various people in the IT and business world. My own take is quite simple, Vista is an Operating System in which case it provides a 'desk' on which to run various applications or applets. Windows XP is also an operating system and also ran most things I need so why would I upgrade?
1) If it was free then I might upgrade just to get something that looks more modern but it is not free, it is pretty damn expensive in fact.
2) OK so it costs money, I therefore have to weigh up the cost/benefit ratio and this should help me decide whether the big dollars is worth it. As far as I can see, for most users anyway, particularly business users who prefer not to use bells and whistles, there is precious little value that it adds. One of the biggest selling points was a snazzier interface but this only came with the ridiculuous expensive and humerously named "Ultimate" edition so most people didn't benefit from this. Why would people want to pay massive bucks for a snazzier interface if that is all it is?
3) It is supposed to be more secure from hacking etc but we were convinced by MS that XP was secure so has something happened since Vista was released that has made XP less secure? If in fact Vista was basically unhackable whereas XP was certainly vulnerable in some areas (and perhaps there were many latent security problems waiting to be discovered) then this would be a reason to upgrade maybe, but it isn't and we still get patches for Vista, obviously the fundamental security model is still very lacking. Still no reason to upgrade.
4) People have complained about lack of driver support but this would always be the case with new operating systems and to be honest i think most people would bear with MS as the drivers are developed if this was the only issue with Vista. What MS seem to have forgotten is that most people in the world still use XP so hardware manufacturers are not in a rush to write Vista drivers!
5) OK, let us assume it was not so expensive for nothing much, then we would autmoatically upgrade our current (probably XP) OS to Vista? Not on your life as far as I am concerned. For some reason, in supposedly going back at least partly to the drawing board and coding Vista, we could have reasonably expected a load of bloat and slowness to be cut out, after all it does not need to support 16 windows applications (does it?) and there must be other stuff which is basically redundant. They could simplified lots of the Windows API stuff and generally made it AT LEAST as fast as XP by the time they added in some new bits but no sir-ee-bob, it is slower, noticeably slower except on the latest machines with 4 cores in their processor which can pretty much handle it. The problem is, all that hidden power being used to run the OPERATING SYSTEM is not available to run what needs to be running, i.e. the APPLICATIONS. I'd rather run XP on an older machine and still have loads of power to spare for my apps.
6) All of this performance hit would be forgiveable if to get ultimate security (which Vista is striving for presumably) will always cost loads of processor cycles and memory overhead etc but interestingly the latest incarnations of Linux are much more secure than Vista and run much faster too. Why? Because they have a good security model that does not require massive OS overhead to manage.
7) I've always wondered why Windows XP and Vista make generous random use of the hard disk when I have not noticed it once on Linux. Linux installs and removals are quick and painless, Windows ones can take hours! Despite Linux potentially being very flaky with all those grubby programmers having fingers in pies, it is, I am sad to say, scoring higher on my useability list than Windows! The only one thing that is lacking in Linux but getting better all the time is the number and quality of applications available. Office, internet and email are fine and these are 95% of what i use anyway. The development environments are not quite up to Visual Studio quality but they are very much useable despite this. There are even cool programs in Linux that you can't get (at least for free) on Windows including XTrkCad a model railway cad program.
8) Sorry MS, you have well and truly missed the point with Vista and you probably know it so stop telling us we desperately need Vista and go back to the drawing board!