If you can make it past the old-fashioned controls and have the will to face its relentless challenge, Prinny 2 is an operation worth engaging in. Just remember that throwing your PSP out of frustration is a bad idea.
For Disgaea fans who want to see the lovable prinny losers get punished over and over again due to the demanding difficulty level, I could see it being a smart purchase. Otherwise, try before buy is the best advice I can give.
Only attempt this game if you are looking for a challenge, otherwise you are unlikely to finish. If you can get past the main story mode, there is a fun re-play mode, but it will likely go unnoticed due to the game's punishing difficulty.