Brings back memories...
Its a pretty unique game with a ton of depth and replay value. You can think of it almost as a cutesy Armored Core (instead of a rocket launcher you get boxing gloves) with easier controls and a very fun multiplayer. The meat of the game is an arena mode. If you beat an opponent, your reward is that you steal one of their parts. As you fight on you will continue to build your robot into the perfect cutesy killing machine. Sounds cool eh?
Looks like the game goes for $7 on ebay. That might be the best $7 you ever spend (just make sure you have a few people to play with!). I'll see YOU in the Robo Pit of cutesy death! Or not, but... yeah that was lame just buy the game k...