Tycho at Penny Arcade has pointed out that there’s a demo out for this game and that it is “shit hot.” I will not argue.
I’ve played through the one level in the demo now probably about six times. It’s really fun… I think it may be disappointing in the full game not to be able to play as any other faction (at least not in the single-player campaign), but being able to choose the secondary weapons for each of your guys is pretty neat. Destructible environments and line-of-sight, as well as the ability to use extra AP for increased accuracy or save some for attacks of opportunity, are all pretty awesome as well.
The game is on my Christmas list now. If you have a PSP, play the demo. It’s worth it.