Although the controls are easy, the action is anything but. They might look like stormtroopers and pour out of magical closets in one-to-three-man waves, but the Helghast are a formidable enemy; most of them are smart enough to hide behind cover while fighting you, and the really scary ones carry powerful shotguns and toss grenades to flush you out of hiding. They're also fond of traps, and so you'll constantly have to deal with hard-to-see mines, laser tripwires and impossible-to-hit spider robots that explode when they get close to you (or close to an enemy, which makes them fun).
You've got a few advantages of your own, though; each stage is filled with weapons chests (which pack guns, explosives and health packs), and a quick life boost is usually just a smashable crate away. There are even a few times where you'll get to pilot a big, powerful vehicle, like a tank or a hovercraft, that can smash through the Helghast with satisfying ease. (Of course, these points are usually where the Helghast start carrying missile launchers, so the benefit is negligible.)
In addition to the lengthy campaign mode, Liberation throws in a bunch of unlockable challenge modes - essentially quick, pick-up-and-play skirmishes with simple, pre-defined goals - that can boost Templar's abilities. It also features a slew of multiplayer modes, including a two-player co-op run through the campaign, a six-player deathmatch and team-based capture-the-flag, team deathmatch and assault game modes. These are incredibly fun if you've got six people with PSPs together, but if you're not so lucky, a downloadable patch enabling infrastructure play will be available soon from the game'sofficial site.