Prepare to have a quite a fight on (and in) your hands.
There's plenty of guns spread out across the game. You start with your standard ISA assault rifle. Along the way you'll come across the enemy Helghast assault rifle, revolvers, shot-guns, missile launchers, chain-guns, and more. There are also secondary weapons available. These include grenades, smoke grenades, and mines. Finding C4 explosives will also be a requirement for some of the mission objectives. For as many weapons as there are, you're only allowed to carry 1 primary and 1 secondary weapon at any given time. A couple of drivable vehicles will also make an appearance, and there's even a jet pack!
Thankfully you won't always have to face the missions alone. Some stages will have you paired up with a team mate to whom you can give orders. The control system makes giving those orders quick an easy. Even when you haven't dished directions out, they can usually hold their own; however you will occasionally have to provide some medical support by injecting them with health syringes.
The single-player campaign is a decent length. There's 4 missions each with 4 stages. Each stage can take you anywhere from 15 to 35 minutes to complete. On the first run some of the harder stages may take as long as an hour.
The potential length of each stage is one of the games set backs, as there are no mid-stage save points. There are check points which are decently spaced out, but if you have trouble getting through the final stretch of a stage and have to stop playing after 30 minutes, if you want to turn the game off you'll be starting that stage all over again. I prefer my hand-held games to be able to provide short bursts of entertainment that can be frequently saved and continued on with. Half an hour was too long for me in between stages.
The length of the stages can be credited to the challenge of the game. Planning a strategy in tight place may take a few rounds before you get it right. After all, it's not always easy trying to take down a target that's off screen and has a missile launcher with enough range to target you and fire homing projectiles! But my point, is that the level designs are straight forward enough so you'll rarely find yourself wondering where you should be going.
Finding bonus items aren't always as easy. In each stage there are a set number of briefcases hiding about. Each briefcase holds money. Get enough money and you can start upgrading your weapons. But the upgrades definitely don't come cheap.
Points will get you character upgrades. These are acquired by completing bonus missions. Bonus missions are unlocked as you complete each mission. There's plenty of bonus missions to pick from but they do repeat in each set you unlock. There's defend-the-base-missions, beat the clock races to the end of a course, missions where you have to shoot so many targets before time runs out, and more. The better you do, the better the medal you get (bronze, silver, or gold). The better the medal, the more points you get. Upgrades include being able to hold more grenades, more syringes, more health, and plenty of other ones. The plethora of upgrades to earn, means the bonus missions will add a lot of replay value for the completionist. But like the rest of the game, gold medals won't come easy.
Plenty of intense fire fights with a range of weapons to choose from and extra value added with each mission you complete and multi-player availability will keep you busy for a while provided you don't snap your PSP in half.