I like the basic gist of this (and Canabalt) but I wish there was some sort of progression to make you feel like you were actually going somewhere. I'll only play a game a few times to see how high a number I can get. If there's different stages to unlock I can stay addicted for much longer.
Okay, somehow I managed to become completely addicted to this. (Mostly I'm addicted to the song, and my "this game needs stages" suddenly became "OMG I gotta get farther next time!" when I realized a) the Dolphins come out every 5000 points, and b) I really want to stay alive long enough to hear the song play all the way through.