It was a lot of fun to play this game. The story is wonderful and the game mechanics are fresh, creative and innovative. You really need to cooperate with your friend, else you will get nowhere.
I also feel like I bonded a lot with my friend because of the game.
I loved it!
Pros:
+only one person has to buy the game (definitely worth the full price)
+story and narrative (emotionally touching)
+characters
+character development
+character and world design
+cooperation as the core mechanic
+a lot of diversity in gameplay (you get different gadgets for different stages of the game)
+atmosphere
+soundtrack
+length (neither too short nor too long)
Cons:
-I personally had some lags from time to time which could have been due to my internet connection though

TLDR: If you want to have fun in a cooperative game with a friend, I highly recommend It Takes Two. It is fun, divers and the story is beautifully reflected in the world.

-Etteleawen