Disgea is one of my favorite PSP games (even though it is a port of a PSI game), so I was interested to see the IP used by Atlus in an original PSP game. Prinny is above all a game for hard-core gamers, you have a thousand lives and even on casual level difficulty it will take you a lot of those lives. Prinny is an excellent platformer that shows off what you can do with the PSP hardware if developers would take the time to actually make original properties.
Graphics: It is a beautiful 2/3-D game with some interesting particle effects and a nice twist when you use the air attack.
Sound: Good J-inspired soundtrack with nice voiceover work.
Gameplay: Brutal, but fun.
The other developers need to take note of how well games can work on the PSP if they would simply stop porting old IPs.