Vistatic first impressions
So I finally managed to get Vista installed last week, and have been using it a bit since then.
Now I know this might not be what you'd expect me to say.. but I think I prefer it over XP already. It's definitely an improvement in some ways!

The Start Menu has been hidden away, and replaced with some icons for commonly used items, plus a box to type in which will "do what you mean", a-la Sherlock and Quicksilver on the Mac, Tracker on GNOME(Linux) and Launchy on XP. FFS, finally! So that's a big win, IMO.

Next up, the user vs administrator separation. Sure, it does seem annoying that you have to stop and Authorise actions, but you know what? What is a good thing. I *like* knowing that run-away apps or naughty programs can't just sneak around modifying firewall rules or any old system files without my permission. You only need to do this authorisation stuff when you're installing new programs or modifying lower-level settings, so after your initial period of setup it doesn't get in the way. I'm not sure why there was such a fuss made about this. (Or maybe I'm just used to having to do it occasionally, having used *NIX and Macs before?)

I heard a lot of complaints about performance, but it doesn't seem too bad. Startup time is comparable to XP, possibly even slightly faster! General use, clicking menus, loading programs, etc seems fine too. Copying files, which I've heard gripes about, seemed to take longer to start copying than reasonable (ie. more than milliseconds) but wasn't what I would call delayed. The new File Explorer windows take some getting used to as they've changed the behaviour to be more like the Mac and Gnome UI, but still keeping aspects of the old way. I haven't made my mind up about whether it's easier or harder to use, yet.

So far I've only tested the in-game performance of Crysis.. at highest detail level, yeah, it ran a bit slow, ~15-20 fps with some hiccups.. but then, in highest detail, under XP, it also runs like a dog.. I think i lost about 5fps going to Vista, but keep in mind that under Vista it runs in "Ultra-high" detail, vs "High" in XP, and thus it's looking nicer in Vista in return for those FPS I lost. I'll need to test some other less stupidly-poorly-performing games too.
And probably buy some more RAM now I have an OS that can play games AND handle 4GB. :P
(Windows XP famously won't deal with more than 3GB of RAM)
But the complaint that Vista runs games at literally half the speed of XP doesn't seem justified.

Driver support: Well, my nVidia 8800GT and the Creative X-Fi were supported by 64bit vista drivers available from the manufacturers website, and nothing has crashed, so that seems alright. I'm afraid I don't have any exotic hardware in the gaming machine, so haven't got anything else to test! The various features provided by the motherboard (usb, network, etc) were all supported out of the box by Vista fine, and I wasn't surprised that my common USB devices also were supported.
I have a $3.00 USB MIDI adaptor winging it's way to me from the distant lands of China, via eBay, and that'll probably be more of a test :)

Software like DaemonTools worked just fine.

I haven't encountered any of the DRM that is meant to be under the surface, yet. But then, that would only apply if I used the machine for media (music, video, etc), rather than just gaming and surfing the web. (I still boot into Linux or Leopard for anything else!) However it does worry me that it's there.

Some gripes:
* Modal dialog windows are STILL not resizeable. Come on! Why not? What's wrong with making the "Save As" dialog box bigger than a postage stamp? On modern monitors, it's getting stupid.
* The default 'Off' button in the menu is actually Standby. You have to get into a little side-menu to get to the "Restart" and "Actually turn off damnit" options.
* Erm, it DID take me 5 attempts and a new hard drive to get it installed, although it was easy when it finally went on.
* I did note that Ableton Live (6.0.10) worked fine with DirectX input/output, but when I tried to use ASIO i/o everything went silent. I have no idea if that's Creative or Ableton's fault, but Live 6 is fairly old, and I had forgotten to switch the soundcard to 'Music production' mode. (The X-Fi is unique in having modes for Gaming, Music and Music production.)
* Windows still doesn't automatically pick up nearby printers. OSX and Gnome have been doing this for ages.

A note: All of this was tested on a recent copy of Vista (64 bit edition) with SP1 streamlined, and the latest drivers for my sound and video, on a high-end machine (Hitachi 500 GB SATA HDD, Core 2 Duo 2.88 GHz, 2 GB DDR800 RAM, 1GB ReadyBoost). I suspect this helps matters - I've heard from friends that SP1 made Vista usable, and that driver support was terrible initially, but decent now.. and I am running it on a moderately-well-specced machine.

Conclusion: I'm still going to continue to use Linux and MacOSX more than Vista, but all-in-all, I don't think Vista is as slow and unusable as its reputation. I don't see myself going back to XP.
On the other hand, it's interesting to see that the noticeable improvements have been blatantly nicked from its competitors, and nothing particularly interesting has been added beyond that.. and in return it's bloated out to using a huge amount of RAM and disk space.