This is one of my older games...but I'm still going back to play it...
The battle system is really intriuging. You set commands for the B, A and X buttons, and the R+B, R+A, and R+X buttons. The commands will be your weak attack, strong attack, special attack, spells or healing items. You can also do a max combo of 3. You can link any combination of attacks, or do a single spell (you will be able to link attacks and spells in PSU). The battle system can become really fast paced and enjoyable when you get into the game.
The graphics are pretty good in the game. They're nothing too special, but you can tell what everything is if you just looks at it.
The music is eirie, and has a sci-fi tune to it. While every stage has different music to it, they are all "different" from most other music that you will ever hear.
The replay value is the best feature of this game. It never gets old. After you beat Normal mode, you can succeed to Hard mode. When your done with that you have Very Hard, then Ultimate. If you can get a few friends into the game, you can play four players at a time. The game becomes a lot easier if you have a balanced team of killing machines on your team (like I do ;). There are also lots of weapons that will keep you wanting to play the game for a long time.
This game is definitely one of the best games on the Cube, and it will keep you going for a long time.