This game isn't that bad.
Sure it gets annoying pretty fast when you are the one trying to throw a grenade but can't because someone keeps shooting at you, or you where pushed of a ledge by an explosion that barely touched you, but truth is, I think that's something good.
It makes this game something new, but at the same time familiar in some strange way. (It also gets rid of most people who are rage-quit prone.)
It's also highly re-playable, as you probably will want to get those better items, or that emote you saw a friend do last night when you played 4 player co-op through the whole game on extreme, wich really lives up to it's name, though it's THE most entertaining co-op experience most players will have for a long time.
The competitive online play is really hard to get in to, and in my opining isn't as fun as the campaign (when played with friends) but is worth mentioning, as the smaller maps can be really fun when played with likely skilled players.
The story is a little shallow, with close to no named characters, but it's also a second side to it, as in some games there are way too many names.
The graphics and sound are very well done, though most text could have been a little bigger as not everyone have a big TV or an HD one.
Also the way the splitscreen, splits the screen isn't very good for smaller TV screens, as it uses roughly 1/4 of the screen for both players.
To wrap this up, this is a game for you if you:
-like a challenge, and don't mind the game hating you.
-have Xbox Live Gold.
and like blasting insect-like aliens to bits.