Exactly, 3d engines ... Final Fantasy 7 looks really bad. But then again you have to see for yourself. Metal Gear Solid looks horrible with it's jerky models but I still can play it for the 1000th time because the gameplay is that good.
If you played those games before and you like them enough to play again then I don't have to tell you to go play them. Just go and play
If you haven't played some of those titles then definitely check out the gameplay videos and see if it suits you.
The problem is buying them
again for PSP with the
money you could spend on games designed for PSP you haven't experienced yet.
Just ask me if you are looking for a game in specific genre so you don't have to replay titles you already played.
E.g. I really recommend Crimson Gem Saga - Korean made game (for PSP, later ported to iOS) in vein of Final Fantasy and Chrono Trigger
