Here are my biggest problems with Vista right now:

1. Sound periodically stops working.  This is kind of annoying.  At first I thought maybe it was an iTunes / Vista compatibility problem, but now I’m pretty sure it’s not.  I’ve had sound cut out in World of Warcraft, Ventrilo, and iTunes.  Rebooting fixes it, but strangely there are sounds from the OS as it shuts down.  I’m sure this is probably some driver problem, but I’m a little paranoid about updating drivers.
2. Hold ‘Em, a Vista Ultimate add-on, looks pretty cool.  Except that all the text flickers like crazy.  So I looking around on the Microsoft site – nothing in the knowledge base.  I did find a discussions (that I would link, but I closed the browser already) in their community area.  It seems it is a problem with the nVidia drivers.  Seems strange that a bug would show up in text rendering in a simple game and no where else, but alas that appears to be the case.  And I’m running the “non-beta”, “certified” driver too.
3. I think there must be a major memory like somewhere – either in Office 2007, the Sidebar, or IE 7 (possibly related to Flash).  My computer has 2 GB of RAM, 2×3.6ghz HT Xeons, and an nVidia 8800 GTX and things get really slow sometimes.  I’ve even had them come to a screeching halt – this never happened on XP.  I also only get a 5 on the Windows Experience Index, which seems kind of low give that much horsepower.
4. Alt-Tabbing between a full screen game and Windows is pretty chunky.
5. Lack of drivers – I want to use the cool features of gaming keyboards (I have a Logitech G15 and am also testing out the new Razer Tarantula).   I’m afraid to install the XP ones.
6. (Yeah I know I said 5.)  The freaking security alerts get really annoying.  Those Mac ads are right on (and especially hilarious if you have used Vista).  Another annoying thing is that I have to run World of Warcraft in Administrator mode to get updates to install – what a hassle.

To be fair, there are a lot of things I actually like about Vista (one of the two reasons I haven’t rolled back to XP – the other is I like testing out the cutting edge stuff).  So I will write a Top 5 things I like about Vista.