You don't have to be a fan of Mario or RPG's to enjoy this perfectly designed game.
The biggest innovation with the latest instalment of the franchise is the fact that you now not only play as Mario and Luigi, but Bowser as well. It was probably only a matter of time before Bowser got a leading role in a game, and although Mario and Luigi's name appear in bigger letters on the box, it is actually Bowser who has a more meaty role in the adventure. You'll be playing as the Koopa King for probably more than half the game (although the time spent playing as Bowser and the Mario Bros. is split up pretty consistantly. It's not like you'll be playing as Bowser for one half of the game, and then the Mario Bros for the other half, just to clarify). Thankfully, playing as Bowser is a lot of fun. And you can switch between the Mario Bros and Bowser at will. That of course leads to some pretty awesome puzzles and minigames that I certainly won't spoil for you.
However, while the unique RPG combat system is amazingly fun, it's the game's brilliantly written script that captured my interest. This is, simply put, one of the funniest games you'll ever play.
Between the addicting gameplay, the hillarious script, and the beautiful presentation (did I mention the game looks fantastic? No? Well it does) there's no doubt that this is one of the best games on the system, and easily the best Mario RPG ever.