It's a decent game.
Don't expect more from it though...
It turns out good on how the "life" system works. You have a maximum of 4 marines. But it's a bit disappointing, since you can only use one at a time. And if one of them dies, you get to replace them on the spot with one of your remaining marines. And if you want more "life" all you need is to find the different marines scattered throughout in each maps. It's not that annoying to do so. But you can only have 4. Tsk. Tsk. A pity. They could have added a multiplayer campaign(co-op).
There are 15 or more marines to find with each having there own personality. It made the game interesting for a while but reverts back to mediocrity when I found out later that they don't really contribute to the story except for shooting stuff and getting the job done.
And if you finish the game, there are unlockable extras that'll maybe interest you for a while. But that's just it. It's a generic run n' gun game.