Gears of War is a playable mid-80's action movie. It's corny, intense, over the top, fantastically entertaining on the first viewing and a lot of stupid fun to be had one evening with a friend.
I played through the game with my brother. It was seamless in that you really felt as though you were a part of this sci-fi action movie that was unfolding in front of you. Think Predator with even less reason to see it again. Kind of fun, certainly not too difficult on the standard settings.
As far as the Multiplayer aspect of the game, it lacks ingenuity. There are hardly any options beyond simple "who can kill more" team against team games. The control scheme bogs the action and is needlessly complex. A lot has been made of the ability to take cover in real time in the game. Well, in order to compete at a reasonable speed either in Xbox live or System-link play, you must hold the "dash" (A) button at virtually all times. Why not just make the sprinting speed the default speed rather than forcing the player to hold down one button the entire game?
Not much about Gears of War is worth replaying.