And THAT is how you put a bunch of superheroes into a PSP
Take the UI, for instance. Every button on the PSP is packed with functions, but they all make sense, and after you learn how to make a move you don't forget and have to check to what button it was mapped. The triggers work as modifiers, but they also have lots of extra functionality that actually makes sense, like pressing L+R to block, or L+R+a direction to dodge. The same goes for the D-Pad and, in a really clever move that should become a PSP standard, holding a trigger turns the face buttons into a "second analog" that controls the camera really smoothly.
Also, the game has lots of nice stuff that take advantadge of the PSP's online capabilities. You can play on line or ad-hoc, upload your statistics to the MUA site (which unlocks a character) and, simply put, milk everything your PSP has to offer.
The game itself is what everybody else is saying it is: X-Men Legends, just much more fun. Finally combat feels like something more than button mashing. You can grab enemies, punch them, throw them and interact with them and your superpowers in lots of ways. A memorable moment that made me laugh out loud involved Deadpool taking a stick from an AIM agent and then beating him over the head with it.
M:UA still doesn't match the first XML in that the story is a little worse, more generic, to fit characters in, and you still don't have an entry character you can identify with, but it's a huge step up from XML2 story-wise, and from both prequels in every other aspect.
So a great port of a great game. Who'd have thought. Other developers really need to look at this one for tips on how to shrink down a PS2 game to a PSP without losing too much in the process.