Ingenius game design but novelty wears off fast.
I probably would have enjoyed Patapon more if it weren't a portable game and I weren't trying to squeeze in sessions on the subway or at my girlfriend's house while she's watching TV or in situations that I typically make use of my PSP. Being a rhythm-strategy game, Patapon requires your full attention for extended periods of time (some levels 10 minutes or longer) and it's not something you can play on the go with other distractions.
But it sure makes a great first impression. Gameplay is lively, simple and fun. The developers totally understand how to start you off simply and then gradually pump up the complexity as you play farther and it honestly offers a decent challenge without becoming annoying.
But over time, the game starts to wear thin more noticeably than others b/c the gameplay mechanic is so simple and it can become a bit of a grind. The same problem afflicted Puzzle Quest, an otherwise fantastic game with a repetitive core mechanic that, for me, just wears thin after a certain point.
Patapon certainly deserves credit for charm, creativity and a great price-point for what you're getting. It's just a shame we don't have the option to play it on PS3 instead on-the-go with the PSP.