No matter how you look at it - Vista's image is unfortunately tainted (but it has still much more marketshare than Linux+Mac OS combined: http://marketshare.hitslink.com/operating-system-market-share.aspx?qprid=10 !)
But, anyway, what caused the negativity? I must admit that I am a bit baffled - i use Vista since June 07, and had zero problems with it. But I admit, I ran and run it on sufficent hardware (Core 2 Duo, much ram)
I think the main factor is that much more people use computers now than in 2001, when XP came out. And thus the user base was smaller but contained much more technicaly savy people (percent wise). XP was far from perfect when it was released (Vista's RTM state was much better), but users back then were more prepared to deal with technical difficulties. The most used OS when XP was released was Windows 98 after all, and no can deny that it was crashy and required some "skills".
Now when Vista came out, XP was on market for more than five years, a whole generation of computer users knew nothing else but XP. So even using another system than XP was quite an adventure for many people. No other Windows OS stayed that long in the market, XP became "teh windows".
In that light some initial quirks of Vista became grossly overstated, minor problems drivers were blown out of proportion. Driver issues always appeared when a new windows OS was released (I can remember how crappy the first generation drivers for Windows 2000 were - shudder!) but because there were so many computer novices like never before when Vista appeared, or people who knew nothing else but XP and never used any other Windows OS (or any other OS) things, that were fairly standard with EVERY windows (and OS) release, became totaly overblown with the Vista release.
Another thing were the hardware requirements. Now, every new windows used more hardware resources than its predecessor, but, again, because of the unique situation in 2007 compared to other windows release dates in the past, people just "forgot" that rule or never learned it in the first place.
Microsoft handled the Vista release like they handled every other windows release in the past. I think that was the downfall. MS didn't see that the userbase changed too much compared to 1995, 1998 or even 2001.
Now there was of course the DRM fud and all that, but slashdot and co badmouthed every windows release, so I don't think that this was the main reason for the negativity.
Well, this is just my opinion anyway, what are your opinions, why did Vista get such an image?