Innovative and fun as hell
If you've played Paper Mario, or the Mario RPG games for Gameboy Advance, SP, this one follows the same formula. Mario fans will really enjoy this game. On the surface, the game does not look very deep, but it is. There are plenty of items to collect, and many things to do. More importantly, this game is loooong. It is just a very well crafted RPG with awesome and plentiful puzzles, great "paperish" graphics, and Mario themes all the way through.
Despite being awesome, there are a couple of problems with the game, worth mentioning: You will spend most of the game talking, at least more than half of your time will be spent doing this. You will also spend a great deal of time backtracking, and wondering where the heck you are supposed to go next, walking around for 45 minutes, until you finally find that random person that you have to talk to, to advance the game. This is a thing that is used a LOT in RPGs, and needs to go. It is a pointless timesink, in my opinion. If you don't have a lot of patience, rent this first. Another problem is the graphics. Although they are innovative and colorful, textures are burry, and there are many instances where upon looking at the graphics, you will think the graphic designers were lazy. Still, they are not bad, and when playing the game, you'll think you were in a wonderful cartoon.
Overall, despite some minor problems, the game has a lot of charm to it, and is an awesome RPG and Mario game.