It's too early to say for sure...

But Rock Band might be the best $170 I'll ever spend.

Just picked it up today, played for about four straight hours with my friend Tom. We laughed like idiots and rawked like kings. Not really kings. But perhaps a viceroy or something. This is NOT a game one should play alone. This is a game for people to play together.

(I'm taking a break right now, because my roommate just got home, and he's now perched behind the AWESOME drum kit)

OK - an hour later, I'm back to finish:

To catch up, I'm writing about how much fun I'm having with the new video game Rock Band. It looks beautiful, plays great (though it's not nearly so difficult as Guitar Hero III, particularly on the easy settings), and there are moments (even as early as the first night) where you become really immersed in the game. You really feel what's going on with the rest of your band (particularly the drums) and can enjoy "playing music".
As far as first impressions go, Rock Band is great. My roommate finished doing the drums for two songs and singing one and went right into how he's going to have a lot of fun practicing for our battle of the rock band party in a couple of weeks. It's already the most fun I've had playing a game this year (and I've had some REALLY good gaming experiences this year) and it only looks to get better.