Alright so I picked this up today.
Here's what I've got so far...
Single player campaign: Terrible fucking dialogue. So stupid. The story is eh but not cringe worthy so far just utterly predictable. While the subject matter isn't always generic, the way they go about it is, unfortunately.
Single Agent/Team Based Combat: Very cool system allows you to hold select and choose between the 4 characters of your squad seamlessly at any time in the game to play whichever agent you want which allows you, as a single player, to set up combos with 4 unique characters and weapon styles which has a pretty wide range of possibilities. There are skill trees for each individual character as well as 'team perks' which apply to an entire squad, so you can really set up your team just how you want it. This part is pretty well done and the skills are for the most part well thought out and useful.
Controls/UI/Movement: Control scheme is fine, the movement is great with the speed of vaulting, rolling and instantly being able to take cover near pretty much anything with just the O button. Actual movement of the character can be a bit odd (read: fucking unnecessarily weird) if you're not particularly skilled at controlling the character with both sticks at all times. It requires coordination and it doesn't ruin it but it's not very easy to flow with, either. Not a game breaker, however. The aiming UI is cool but a bit sluggish. I have max sensitivity and still feel like I can't get to my targets quick enough. Also, the UI is a bit massive and I don't a see way to change it, so expect your screen to be full of shit anytime you're shooting at something. It's okay and I got used to it, but it's not exactly sleek in the slightest.
Small con: You have to hold triangle to pretty much pick up/do any action at all in the game and it's fucking retarded. A little timed bar pops up and you have to walk up to fucking everything, including the trivial shit, and hold triangle and wait for it. Hacking a computer I can understand the immersion of timing it so it's not an instant cakewalk through security systems but it does not take 15 seconds to pick up some ammo on the ground for fuck's sake.
I'm a huge fan of co-op shooters since I have a couple of close friends that I have a blast playing with and this is worth picking up for the co-op experience. There's also a game mode called Echelon which can be played co-op/online which is basically you and your team against waves of enemies for a change of pace. Pretty cool.
The weapons and chain combos are cool as fuck. The general selection of non-Xenotech weapons isn't really groundbreaking, typical ARs and pistols and whatnot.
The environments and atmospheres aren't too bad at all and give you a lot of options on cover and whatnot with some areas proving to be well designed combat areas.
Enemy AI is pretty decent, I started on hard and have been fucked up in a couple situations and I'm a pretty well versed player when it comes to any shooter.
Overall, 6-7/10 for providing a decently entertaining and unique single player experience with a kick ass co-op element but completely lacking in interesting story elements/dialogue, etc. It's actually painfully stupid at times. I'd say the rating of this game really depends on if you have someone to play it with or if you can enjoy strangers company online through co-op because it's not going to be for everyone with just the single player.