I've been using Vista now since late Feb early March and one posative thing I have to say about it so far is I haven't experienced "WinRot" yet, which killed my XP system as soon as a month after use.  Another thing is I can go weeks without ever having to reboot whereas with XP within maybe a week I had to reboot.  It keeps chugging along!
Another cool thing, no more defrag.  Rather, it works in the background when you're not awake.  I know a lot of geeks and pro users like the little dialouge with the percentage and graph and whatnot.  I was in strong disagreement with it's exclusion when MS's plans were revealed as well, but now that I'm using Vista it's not a big issue.  I never even felt I had to defrag because my drives keep running smoothly. Â
The problems I have with Vista is the inconsistancy in the UI, like the misuse of fonts (which can be fixed) or *ahem* the add font dialouge (salt, meet wound). Â
Plus, while backup is better than no backup, Vista's backup kinda sucks.  Once your hard drive is full, you're fukked.  I had to erase the whole damn thing and start over.  And unlike say, Leopard, it won't replace older files or even give you options it just spits an error at you saying the disk is full.  It doesn't even give you a wizard, that's so unlike Microsoft to not offer a wizard at every available oppertunity!
Weird things sometimes happen, albeit small.  Flash has issues with Vista, sometimes I have to reinstall it.  As does iTunes (the UI doesn't refresh sometimes, so you gotta minimize and restore once in awhile), Media Player won't play DVD's (my biggest issue with Vista), my Wacom tablet sometimes will stop working... but the thing is that these are all third-party problems.  All but the Meida Player issue is addressed by third parties as their problems on their sites.
The Ultimate Extras so far have been anything but.  We're still using a preview of DreamScene, buggy at that.  I'm kinda miffed about that.  So far we've got a game of poker which I never play, BitLocker which I never use, and the aforementioned Dreamscene.  Bah.
Overall, Vista couldn't be better in the sense that it does its main functions well.  The problem I have is the new inclusions or lack thereof.  Like Backup, Movie Maker and DVD Maker are sad, sad little apps.  Photo Gallery is good if you don't own something like ACDSee already.  Media Center is worthless to me as I already own a DVR for my Dish, but it is damn nice, I'd say it gives even Apple a run for their money in UI design.  Performance wise, it's not as big a hog as some people think.  It's not sluggish, and I have a P4 Northwood chip.  Ram is fairly inexpensive, though it's on the rise nowadays to keep up with the pace of technology, I have 2 GB and it's fine but you could always use more.  To some this is a negative point, but technology is continually requiring more processing power as more and more things are done on the PC, and more things are handled on the OS. Â
So that's my long-overdue experience with Vista.  I'm happy with it, though if I could go back I'd probably get the Home Premium version as Ultimate, even though I paid for OEM, isn't all that Ultimate.  Once I see what Vienna is going to be like, I'll decide if or not I'm going to upgrade my PC and stay MS or kill my savings account, foreclose my house and live in my car for a new Mac.  For all the new stuff and things I do like about it I'm just not as happy with Vista as I thought I would be.
My Specs:
P4 3GHz Northwood
Gigabyte 8IK1100 Mobo
Corsair CMX512-3200C2 x4
150GB WD Raptor (Windows)
160GB Seagate 7200.7 (Media)
250GB LaCie d2 External Drive (Backup)
ATI Radeon 9600XT 256MB
Samsung 910T 19" Display