If you want my honest opinion:
This movie leans more toward psychological thriller than horror. I have once before seen this movie and watched it again with my boyfriend who really enjoyed it. Having the main protagonist be both deaf and mute is very interesting. Many reviews say that she is dumb or the killer is dumb but frankly, what would you do in that situation? I find this movie enjoyable to watch and it has many twists. Another thing I would like to add is that yes, it is a bit slow in the middle but if you watch it through it is quite an enjoyable movie. I highly recommend this movie if you are looking for a slasher thriller with a few twists. The acting is pretty good, and their reactions and emotions are thought out and played logically, the emotions aren't just straight fear or terror. (as mostly used in these kinds of movies) but if you are looking for jump scares and screams, this won't be your kind of movie.
Yes, this is purely based on my own opinions, many might not agree or have differing opinions, but I personally think if you are interested in the movie enough to read the comments, at least try to watch it, and if you find it unenjoyable, you can always find something else!
*SPOILERS* I've read through a few comments and here is what I have to say. they nag the killer for being dumb and not breaking through the windows. As you can tell from the beginning when he chases down the main protagonist's friend, this killer likes the game of cat and mouse. He wants to make her suffer, not kill her right away. (as you can also see when he asked the corpse if he should wait longer before going inside.) He likes tormenting her and finds it amusing from the start when he sends her pictures of herself instead of just killing her. Now for the ending where he is suddenly in the bathtub, I have no explanation other than that she blacked out from blood loss.