I had avoided this movie because I really didn't think it was going to be too great. The Netflix description was just something about "a monster that can only be passed on with sex" which sounded like a really trashy movie.
Turns out the concept of what is essentially an STD monster is actually super tense. The gist of it is the monster can only walk, it never moves faster than a walk. It also only tracks a single person at a time, though if it gets you it works back in the line of intercourse.
There is nudity in this movie (surprise?), but it's never featured sexually. You really get a super uncomfortable rapey vibe from the monster, it's not a good time at all.
I recommend watching it if you're a fan of stalker type horror movies.