First of all let me say that a rhythm based tactical combat game mixed with a simple cryptic story will not appeal to everyone. However the game is refreshing in its own way. You have not played anything exactly like patapon and the gameplay itself seems viable, it just goes to show how many more possibilities there are in game development.
You start the game by playing some easy missions just to teach you a few basic rhythms that you will use to command your patapon army. You later learn 5 commands and may have to use all of them within the course of a mission to acheive victory.
There's also a material gathering component, you will need to find secrets to unlock bosses and minigames that will provide you with other essential items. These items can then be used to create super patapons with enhanced defense, speed, attack or in the case of the harder to get materials just be totally badass
You will be equipped with many different classes of patapon for fighting off the zigotons(your sworn enemies) and many boss characters. You will find however that some of the classes of patapon are not really all that useful especially when fighting bosses. In my view though the patapon vs. zigoton stuff is the best, you will have to choose which classes to take into battle and in which combination in order to fight off their units effectively especially because you will undoubtabely be out numbered, out gunned and swindled through the course of the game.
This can get frustrating, but if you let it bother you you miss out on the fun of discovering the best way to fight them on your own, there's nothing more satisfying than being utterly destroyed 3 times and then utterly destroying your opponents the 4th.
So in conclusion, patapon is bassically a trial and error type strategy game, as well as a simple rhythm game with some loot gathering thrown in for good measure. It will easily take up more than 10 hours and possibly even 20 and it leaves you feeling pretty good about yourself and your little patapons.