When recently trying out Bioshock (which is a whole nother post), I installed Vista Ultimate on another HD to try it out and Bioshock with DX10. I couldn't get Bioshock to load in Vista. But I ran Vista for three weeks to give it a good old try. Needless to say I'm back to running XP x64. My primary purpose for my computer (other than writing blog posts) is for photography. Something as basic as, oh you know, file transfer speed is important. Sometimes you have to dump a gig or 16 from a days worth of shooting and you'd like to do it quickly. To that end I own Sandisk Extreme IV CF Cards and the FireWire reader that goes with them. In XP x64 using my motherboards built in FireWire interface I was getting close to the reported maximum transfer speed of 40MB/sec (somewhere around 36mb to be exact). You'd think, something as basic as this would just, well work in Vista. It worked... at 2MB/sec. I just couldn't beleive it. I heard file transfer was slow but geez. I downloaded was is being dubbed as "Vista Service Pack 0.5". It was a huge improvement, I went from 2 to 20MB/sec. Still 50% slower than what I'm used to.
There are a lot of issues that are now reported on the net. Most of them to do with file and network speeds. On the plus side, M$ did an amazing job with the Aero Interfaces performance. I don't actually think the interface is that good, but they made their attempt at "pretty" and "usable" at least work fast without any noticeable visual lag like simple dropshadows in XP does.
The average user it seems started noticing. Manufacturers are starting to offer downgrades to XP.