Even at $1.99 this bargain bin game is a toss up.
Now, missions are broken down into checkpoints where you can save to avoid those mind numbing restarts which you'll probably need to do anyways due to lack of ammo and or health as this game isn't forgiving what so ever to poor planning. Provided you can find your way to your mission, the main objective is to stay hidden from AI which sometimes can see you through walls, yes I've tried it! Its not that I'm walking too quickly and stirring up noise, it's through a complete "brick" wall the AI can see me and comes straight toward me via the nearest doorway.
Now options of disposal of said AI depends heavily on the mission, though you have guns you can't always use them as such and thus you must rely on other means of knocking guards and other foes out. If you can't kill them the mission is extremely hard as you take forever to hit someone before you can hit them again, if Sam is trained so well why does it take enough time between elbowing people to get shot 4-5 times? You'll sometimes be granted or find stick shockers, air ring rounds or cameras which can also be used to knock AI out, yet the cameras are a little harder to use.
All in all this game has it's flaws but heres how it breaks down. This game gets a 5.0 because I found it extremely difficult, yet that level of difficulty kept me coming back to test my skills over and over again like a good game should. While I can't advise this game as being good I'll say it's not all bad, therefore I give it an exact neutral score.