the short answer is: there is nothing wrong with Vista. The problem lay in the user's expectations.
Folks, Vista is not MEANT to be an O/S targeted at the computing or game enthusiast. It is meant to provide a very low-maintenance, highly secure platform for the 'average' computer user, who just wants to plug in their new BigMoFoCo PC and not have to worry about getting an additional firewall program and setting it up, or an anti-spyware/malware program and setting THAT up, or an antivirus, blahblahblah... they just want a plug-and-play solution for their digital camera, mp3 player, email needs, and lightweight web browsing. And guess what? Vista performs brilliantly at that. Yes, it uses a ton of RAM, but your average computer user is barely even touching the 2GB of RAM that their computer ships with, stock, so it wasn't a huge concern.
Unfortunately, the people who actually talk about and review operating systems are from the (relatively small) enthusiast section of the computing world, so all you hear are the gripes.
Win7 is going to be more along the lines of what the enthusiast wants. It's still needs a little polish at this point, so don't go running out to try to find a beta, but it's looking very promising. (Personally, I use it every day at work, and I think it's teh SEKZ.)
Oh, and for you doofi that are bugged by the prompts for authorization, go to the Control Panel, select User Accounts, and then click "turn User Account Control on or off". Then, you'll only have to deal with a notification in your system tray that says "UAC is OFF! Please address this" If *that* is too much for you to handle, go to the Services menu, right click on the 'Security Center' service, and then disable it. All your annoying notifications will be gone.