First off, I would say get the first Prinny game before diving into the sequel, to get a feel for what it has to offer. Second, if you can't cope with frustration, I would avoid the game entirely, for it is, and I cannot stress this enough, AAAAAAAAAAAAAAARRRRRRRGGGHHH! dificult. A mix of classic Mega Man, Ghosts n' Goblins and a shard of ceramic tile to the temporal lobe, this game WILL make you weep blood. But once you get the hang of it you should have loads of fun.
Since you mentioned final fantasy, I would also rec. Crisis Core, the prequel to ff7. it plays like kingdom hearts but with a slot machine controlling what summons and limit breaks you use, but it's still awesome. Another good psp rpg is the remake of the legendary Lunar: Silver Star for Sega Saturn. A solid story told in fully animated cut scenes, with a flying cat added in because, what the hell.
and finally, I would pass on to you the gospel of Castlevania: the Dracula x Chronicles. A 3d revamp of the saturn-era Rondo of Blood, plus an unlock-able edition of Symphony of the Night, which is a must-play if ever there was one.