I've got a few hours worth of yay or nay action on Pandora after seeding it with some stuff I've been listening to lately, and it just keeps getting better and better at picking music that I like. I've found a few things so far that I'm willing to buy, so it's working, and I hope to God they're starting to make money.
The only thing that I don't like is that it tends to play a few safe songs from artists you've cleared, and I'd rather it just started with new stuff I haven't heard before so I can start training it. Because of licensing restrictions, you can only skip so many songs per hour.
By the way, I might add that having a big LCD HDTV that works like a monitor is great if you have a computer in your living room. It's like I'm using my good old Sony receiver to play music for the first time in ages (not counting parties).