I felt sick afterwards
After playing Spec Ops the Line I felt sick. But I still recommend it for the same reason I recommend the movie "Schindlers List". It most definitely is not fun to play, but there is something there that makes it worth playing and I can't easily put the why into words.
One of the reasons might be that it made me think about the airplane scene out of Call of Duty Modern Warfare in a different way: Why can I exterminate hundreds of enemies in Call of Duty and still feel somewhat normal about it, while doing the same thing in Spec Ops make me feel physical sickness? Hell that I'm still thinking about the game days later is a reason.
I had to make several pauses while playing Spec Ops: The Line and it was extremely hard for me to finish it. One of the reasons (besides the physical sickness) might be the difficulty. I played it on normal difficulty and still got stuck dying over and over again at certain points. For that reason and the reason that the shooting is not the main thing keeping me playing anyway, it might be a good idea to play Spec Ops on a lower difficulty.
I would recommend this game to everyone that looks for something special. And however hard it is for you try to finish it. But don't power through it, give it time and make pauses when you needed.