I can't stress enough how addictive it is with the achievement system on the XBox 360. Racking up gamer points that earn you bragging rights towards your friends is just so immensely cool. I really like looking at what my friends have been doing on their box when we do not have time to play online against eachother. As you may have noticed, I found out yesterday that you can get your gamer card to put live on your homepage. Neat O! So now you can all see - even without a 360 - and maybe you will get annoyed enough to go buy one, if they ever get widely available in stores, that is, and add me (Fehaare) to your friends list so we can compete.
I do miss some things on the box though though: A list of your friends ranked by gamer points and notifications when one of your friends beat your high score in a game. That would be good additions.