Ive just started playing it last weekend in what little time i have

. I find the guns amazing! i find that i fall in love with a gun and just as i get used to it a new one comes on the scene and changes the gameplay once more. I have massive respect for the game on that front.
Also it is satisfying finding out the weaknesses of the monsters and timing your shots to get the crits. The humans are easy, AIM FOR THE HEAD.
the whole elemental thing is well done and it means you have to think about what guns you keep in your inventory to counter certain enemy because some bastards just don't go down to normal bullets.
Now the downside, the quests are repetitive, the world feels lifeless and the main story is throwaway (as far as i have gotten which is only to like level 20).
My problems with the quests are the fact i just don't care what i am doing, i couldnt care if this guy wants his wife rescued because rather than seeing the pain on his face as he tells me, I have to read it out from a notice board. In the end it boils down to, go here, shoot these guys, collect this. This game could have been so much more than that. its not game breaking because the shooting mechanics are epic but because immersion and story rate so high in my game rankings I just get a little annoyed.
My second comment was about the world being lifeless. The game has a wonderful premise but its never fulfiled. All of the npc have about 3 lines on rotation and most of the dialog comes from your hud and not from face to face contact.
My final problem with the game came from the story but that is kind of covered in the quests. all i will say is that the intro movie was fantastic and if they kept that cinematic style of presentation for the main story it would make this game great. i would not care that side quests are like they are because overal i am not to fussed because its so fun sending rockets from a rocket launcher at some alien and watching it explode.
Also this game is hard if you dont have the right equipment. there are some missions which say you should be x level to have a normal difficulty but what they really mean is you should have x gun to have normal difficulty as thats what its about.
overall I play this game for the guns

and eventually for the coop but i am not doing that till i complete the single player.