Patapon came out in Japan recently. I played it.
IT'S AWESOME.
It's a strange rhythm/real-time-strategy game and I say this loosely. You play as this weird tribal race (they remind me of Vikings mixed with Indians) called Patapon that was nearly wiped out in a war. You play as God who beats on godly drums that guides the Patapons to rebuild their lost civilization.

To do this, you play the magic drums to the rhythm of the music. Each drum (coordinated with the face buttons) issues a specific order. For example, playing Pata Pata Pata Pon (square square square circle) moves your troop forward while playing Pon Pon Pata Pon (circle circle square circle) issues an attack. Chain your moves high enough earns you FURRY which causes the music to speed up but your orders have more effect.

Each "mission" has you collecting gold (used to build troops), items or advancing the storyline to rebuild your civilization. You use these items to build troops by combining materials to craft new Patapon. You have various troops such as Speer-chuckers, melee-combatants, and archers. In addition, troops can be customized; not only do the materials you choose to build your troops affect their stats (and you can create super units in this method). Troops can also be equipped with items; for example, melee troops can be equipped with various weapons like axes and swords which affect different armors and enemies to certain degree.

At first I thought the game was going to be repetitive but it slowly introduces you to new elements and troop combinations as well as new challenges. There's mini-games that net you new items (such as having a rock contest with a singing tree) and some of the bigger enemies and bosses are pretty tough. The levels get really hectic and the more badguys you hack through, the tougher it gets to keep up the beat.

The music is awesome. It's like, straight Celtic style music with heavy emphasis on war drums. I love the simple graphics and even though most of the game's characters consist of like... one color, it moves
incredibly fluidly. I haven't traditional animation this fluid since Wind Waker and the style is crisp and sharp on the PSP's screen.
The game comes out in the US in February. It's definitely a fine addition to the PSP's library and is perfect as a handheld game.