I've been running Windows Vista for almost two months now and figured that it was time for a status update. I've already talked about what I like, here are some dislikes that have manifested with daily use:

The security restrictions are very annoying. Many common acts (installing programs, deleting files from flash drives, changing network settings) trigger annoying permission popups. Sometimes a single action can trigger up to three permission prompts! Often the prompts are ridiculous -- such as asking you first if it's ok to prompt you, and then once you click "yes", actually doing the real permission prompt. It's hard to imagine the average user liking this. I am very close to trying to figure out how to disable the popups completely.

The driver support is seriously lacking. Hopefully this will improve greatly by launch time, although it's hard to see it happening in time since there is so much work to do. Most hardware manufacturers don't appear to have any official Vista driver support. A few more have beta drivers. And I'm not talking about obscure companies here. I have two relatively recent video cards (one ATI, the other nVidia) that both had weird quirks under Vista. The most recent drivers from each company don't fix the problems. Luckily, (video drivers aside), the drivers that Microsoft provides with Vista seem to generally be decent, so if they work fine for you, then you won't have any problems.

The semi-transparent "Aero theme" is interesting eye candy at first, but after a while I just disabled it. Often it's a little too translucent, showing too much of the background apps. This makes it difficult at times to read the active window. Sometimes it's hard to even tell which window has the focus! And the borders in Aero mode are really fat and space consuming. If all this isn't bad enough, some applications are incompatible with Aero mode and running them will cause the screen to flicker several times as Vista switches to non-Aero mode to accommodate the app.

Lastly, I have been pulling my hair out trying to get an HP x5400 media center extender working with Vista without success. It finally dawned on me to check the web, whereupon I learned almost immediately that v1 media center extenders aren't supported by Vista! (As a side note, it would have been nice if Vista had given me some sort of message letting me know that the v1 extender was incompatible.) So the millions of people who currently have a v1 extender are getting shafted completely. This is a pretty serious backward incompatibility problem and would be a significant reason not to upgrade to Vista in my opinion, especially if you rely on one of these media extenders. See Jason Tang's blog, Chris Lanier's blog, or this Green Button thread for more information.