You are obviously a much better player than I. I bought it used a while back for < $20, and I really enjoy(ed) it, but I hadn't seen a lot of hype about it at the time, so the (somewhat) unexpected uniqueness of it contributed to my enjoyment. Had I actually sought the game out, and paid $40 for it, I suppose I might have found it less enjoyable. I have yet to open my copy of the firefighter game, so I can't comment on that one.
It may just be that you are too good at rythm games for this one to challenge you, but have you considered the possibility that you may have been concentrating so hard on getting through the game, that you, perhaps, didn't take time to smell the roses. Also, one thing that I really liked was showing the game to my friends (most of whom are non-gamers). It usually gets a pretty good reaction. Maybe you could think of someone who might enjoy it, and invite them over to play it (you don't have to invite them over just to play the game, of course).