Previously, I installed Vista on my home computer. Here are some comments from my wife. I found her feedback interesting because her usage patterns are closer to the average than mine are. She's not a developer (would never use Visual Studio or write a .bat file), and her main computer usage is web browsing and Word.
Here was her list:
I found it interesting that she hasn't mentioned UAC yet. That means that she's getting the security benefits without it apparently getting in the way.