I loved the first film. My wife and I watched it, liked the plot, acting, sex, everything. This one, for whatever reason, Joone felt as if he had to make the sex "dirty". At the end of the day it takes away from the plot, the character and the film to have someone who is a good actor get to a sex scene and have to describe getting fucked in the ass. We see that. No need to say it 20 times, your character that you just spent the last twenty minutes developing wouldn't really say that if you stayed in character.
It wasn't like that in the first one. Now, suddenly, each character has to yell FUCK ME FUCK ME FUCK ME IN THE ASS, where in the first they just did it with the appropriate moans and groans.
None of what I just described bothers me but I know that it makes the movie less interesting for my wife, and probably more couples.
In THREE go back to all of the things that made the first one so good.