This game looks gorgeous. There's no way getting around it, but we've all seen screens and video before, so this comes to no surprise. Developer Guerrilla has definitely paid an extreme amount of attention to detail as they try to get as much horsepower out of the PSP as possible, and the results are simply amazing.
The demo drops you into a Dock level where you basically have to make your way through about a dozen enemies, a few sets of infrared-triggered explosives and deal with a nasty rocket-launching baddie to infiltrate the enemy's base. All in all, it will should take you about 20 minutes to complete after restarting a few times. But after you've mastered it, it will only take a few minutes to get through the level. However, it's enough to show you what the game is all about.