Gears of War is unlike any game I have ever played. I wouldn't consider it a plain shooter because if you run around trying to shoot the enemy without taking cover then you will die... often.
In this game you must take cover to survive. The enemy will also be taking cover while they try to take you out.
I have not played online or coop so I can only speak for the single player game experience.
The game is short. Very short. It took me about 6 hours to complete all 5 acts. The graphics and the gameplay were incredible but the story was not very in depth and pretty generic for they type of game it is.
I finished the game wanting more. I guess I had better get Xbox live to enjoy more of the game.
Single player Score:
Graphics-10
Sound-10
Gameplay-9
Story-7
Value-6