I liked the premise. It's funny when you think about it but it is also something different. The main lead acted really well. I liked her performance and she was really cute too. The rest of the cast ranged from good to meh.
The way this film was treated gave it a really different and unique feeling from the current horror films. The cinematography was amazing with tons of lingering shots, slow pans and things happening in the background. The soundtrack was spectacular and really carried the film, I absolutely loved it. The movie just felt fresh and different and I really liked this about it, don't know how else to say it.
From the start till the end, the movie had a constant slow pace and this tense atmosphere. This consistency was another thing that you don't see in current horror films as usually they start very slow and build up to an big finale. And while this movie was slow paced, it wasn't boring or anything. The slow pace added to the creepiness and complemented the entity as 'IT FOLLOWED' slowly too.
All in all, I really liked this film. I'll admit it wasn't that much scary or anything but the direction of the movie and its freshness/uniqueness really makes it worth a watch. If you're looking for lots of jumpy scares or cheap scares and stuff, you might not like this.