I bought this for my PSP since I really liked the Jak&Daxter games for the PS2. This game did not fail to pull me in and become a true favorite for me.
One thing I never liked about Jak, was that he didn't say ANYthing. Daxter has more personality and I don't miss Jak at all. He still gets to ride cool machines, use cool weapons and explore interesting locale, as well as kill off some pretty gnarly bugs and figure out some tricky moves.
I have gotten to the last and final boss, and I have to say humbly I cannot currently beat it...I dare say it is humanly impossible for me :-). But it is worth buying and getting to try YOUR luck after you get that far. There is much to figure out and explore and collect and it stays true to the style of the Jak & Daxter games I came to love for the PS2.
Another cool aspect of this game, are the dream sequences that are above and beyond the game playing. As you make your way through the game you gain new dream sequences that are fun to watch and play (Matrix and Braveheart reminiscent). As you beat dreams, you gain new powers, moves and gain new secrets...But beware...it takes some pretty fast fingers to win these.
Plus you also get to do Bug Combat as a separate game as well. Along the way IN THE GAME again, you are also collecting bug powers while you play. Bug Combat is kinda fun and is reminiscent of "Rock, Paper, Scissors" as you choose weapons and shields for your bug, to fight the psp bug. One bug tops the other with their choices of shield/spit/claw.
Finally, this game has a guide at the Daxter webpage of the PSP website, if you get stuck. It may come in handy as I found I was stuck a couple times in various locations and had no idea how to get out.
There is not a ton of great games for the PSP out there as I am finding...but this one is my favorite so far and worth the purchase. ENJOY!