I'm gonna toss a vote in for TMNT. After having a bit of fun with Tokyo Beat Down, I went back to see if there were any other beat`em-ups I might want to take another look at. I remember fooling with it a bit a while back and not being too impressed with it. The game definitely has its own thing going on -- not your typical beat`em-up -- but I'm finding myself enjoying it. It's kind of a weird mix of on-rails and platforming/beat`em-up. Pretty cool. I think IGN gave it a "5." Having not yet played through the whole thing, I couldn't honestly say it deserves a better score, but it's certainly worth checking out.
+1
EDIT: Okay...I played through about eight or nine levels, and yeah, it's a "5." IGN was pretty dead on, I think. That said, it's still fun as a guilty pleasure sort of thing.