I pretty much agree with this assessment from spelk over on another forum although I have the PC version and have only played coop to mission 3. Pinkeh is that on insane and why do you think aliens are supposed to be accurate?
The Wargamer | Computer Gaming - Colonial Marines - Not bad
"Seems ok to me (on the 360), so far - about three chapters in. It has Aliens in it, and fast shooting guns. That's about it. It's atmospheric to a point, but doesn't feel as "shit-your-pants" as the previous Aliens Vs Predator game did.
I'm a little sceptical about them using marines vs mercs as well as aliens. As a 'mano a mano' game it doesn't come across as anything other than pedestrian.
Haven't done any online with it, but in the single player (or co-op) you can unlock weapon features and spend points - but it feels very limited really.
Shooting Aliens isn't bad. But overall I'd say if you're not an acid-dripping Aliens fan, you might not want to stump up full whack for this one.
Later...
I tried multiplayer last night and was pleasantly surprised. It does a decent job of creating tension and teamplay, and playing a stalking Alien really is as good as it implies. I think the Alien control mechanic is better than the one in Aliens vs Predator. Latching onto a wall requires a physical action from you (pulling the left trigger) so dropping off a wall to suddenly leap into a marines path is very satisfying. I only played the Team Deathmatch, and it sort of comes across as Left 4 Dead coupled with something like Natural Selection.
Also I played the campaign co-op, and what little I played (over again) felt better the second time around with another person in tow. I think they must scale the enemies you face if you're in co-op, because I actually got to a point where I died - whereas in the single player campaign, I was 3 chapters in and I hadn't died once.
I've seen a lot of the press reviews and the slatings its getting, and I don't think it deserves that much of a pasting. It's nothing new, but it's not a total flop, for me anyway. I don't like these rumours of it being out-sourced so that it's lack of quality (allegedly) isn't wholly Gearbox's responsibility, and they're pointing the finger clearly at Timegate Studio's involvement (a studio I think is under-appreciated for its titles such as Kohan and Section 8 ). From what I've gathered Gearbox was involved at every stage of the game. Single player and Multi-player.
Anyway, as a space marine shooting aliens fan, I'm honour bound to purchase Aliens titles like this, but after some enjoyable and tense multiplayer, along with some blossoming co-op play, I'm glad I stumped up for this title now. I think the press backlash is mainly because it didn't deliver buckets of innovative and new."