I haven't had a chance to check out too many modern Turkish horror movies, but most of them that I did watch were rather descent, with some being great.
I finally managed to pick up Dark Voice (Ses) and give it a shot because of it's lead actress, the beautiful and talented Selma Ergec.
It's a well made movie, with tight screenplay. Direction was well handled and I was rather surprised how some scenes were put, considering that director has no other horror movies on his list of works. There are few creepy scenes, with good atmosphere. I should also point out that editing in this movie is really good. Sound is put to good use here, either sound effects or soundtrack. There are no cheap jump scares with loud orchestra choirs, most of the time score is in the background and never becomes a distraction. Credit rock song also fits nicely with the movie theme.
Acting was good, most of the actors seem very confident and believable. Selma Ergec and Mehmet Gunsur both worked on TV novella "Magnificent Century", and it might be a reason why they seem comfortable with each other in this movie.
screenplay itself is well handled, there are no wasted lines, but it becomes little too complicated with several subplots during the final act, which will make some people confused if they didn't pay attention during several plot points during the movie. In my opinion, it might work better if they kept it simple. I might give it another watch, to see if I missed any details. (shouldn't be a problem, because Selma is charming young girl.)
Ps. It's wrongly marketed. It's not a horror movie, it's more of a thriller\mystery with psychological (or supernatural, whatever suits you the most) elements. There are few creepy scenes, but no gore, little blood, and no violence, so gorehounds and bloodhounds will be probably disappointed.