It's a great game and plays very smoothly and well and is really fun to play, but you get to the end and are left saying "Is that it?" Albeit, there are multiple levels of difficulty, multiplayer, and various other options that keep you coming back, but I just wish that the game had more for you to play. What I mean is that there is replay value, but there's just not enough in general... I can get sick of playing the same ten levels over and over.
Other than that, the difficulty level is perfect because there's always a challenge in each level of difficulty, but not too much, and when you die you aren't punished that badly... It's not the kind of game where you are just playing certain parts over and over so you can get past them; every part is enjoyable.
The graphics and sound are superb, though now that the new generation of systems is out, they seem outdated. For a gamecube, the graphics are great.