Yea, I also had the original PS1 version, but when I heard this was coming out, and the game was fetching at least $150 on ebay, I knew what I needed to do. So I up and sold it and couldn't be happier. All in all the game is pretty much just as good (and better in some ways) then the original PS1 game.
It's got some badass CG cutscenes. I mean the part where the princess turns into that red-deamon-hellbeast thing was awesome. I like that it's a true widescreen game and not just stretched out. Although so then the PS1 version. Other then that, it's really nice. Plus you can turn your PSP off at anytime and start right where you left off (that is unless you put another game in). It makes this game much more enjoyable because you don't have to wait for a save point to stop playing.
Well, back to more goodness.
BTW: This game is freaking deep. I mean I knew it was detailed, but man it's an intricate game.