Ape Escape is a great game, just not on the PSP.
But as you already know the PSP only has one analog stick. Porting a game that was made for a controller with two to a handheld with only one doesn't make much sense and because of this the game doesn't control well at all. In the original game you were able to map four different gadgets to the four different face buttons (circle, X, square, and triangle). Pressing those buttons would bring up whatever gadget you had assigned and you tilted the right analog stick in the direction you wanted to swing or use the gadget. Jumping was used with the R2 button. The same applies to the PSP but since it doesn't have a second analog stick,or a second set of shoulder buttons, you just press the corresponding face button to use the gadget and for gadgets like the Stun Club and Monkey Net you have to move the PSPs only analog stick in whatever direction you want to swing it. This works ok but it doesn't have the same precision or accuracy as the old game and you'll completely miss catching a monkey more than you should in this game. Even some of the easiest monkeys to catch are hard to get. You jump with the X button. Using that button knocks down the total number of gadgets you can have equipped from four to three. The control isn't the only thing that gets in the way. The camera is also a huge pain. It can't keep up and when you get it tight spaces is goes ballistic making progression extremely difficult. You can snap the camera behind you by tapping the L trigger but this never really helps much.
But with all that's wrong with Ape Escape on PSP it does have some redeeming qualities. The charm is this game comes at you at full force. It's a very kid friendly game (and very Japanese) but that just adds to the charm. It never feels like your watching some kids show on PBS but more like a show from your childhood that you feel nostalgia for. The game is also pretty long. It will take you upwards of 10 to 15 hours to finish. But after you feel like your done you have to go back and get all the monkeys in the game to get the real ending. This adds a lot more longevity. Too bad the controls almost ruin the experience.
I played this game back when it first came out on the PS1. I loved it and couldn't get enough. I bought this game out of longing to play the game again and I thought that the controls wouldn't bother me. But after playing it on the PSP for a while I realized that the controls on the PS1 were what made the game. The PSP version of this game just can't cut it. If you have no way to play the original game on the PS1 then I guess this PSP version is worth a shot. If you never played the original game you won't feel the disappointment of knowing what the game controlled like back in the day. But you will feel a sense of awkwardness with the controls.