It looks way better than most Slender-films I've seen. Some pretty cool shots and tricks. I liked the way Slender man was done here. Music was pretty neat, also the flashing lights were done in a delicate fashion. Although one might say that for a person who follows the horror scene they are all pretty easy/straightforward things, even clishés.
I'd say that the acting needs something to it though. What is the objective of the main character? He is waiting for his girlfriend obviously but besides that? He finds out that Slender man is after him and them creepy stuff happens but the viewer doesn't really have an objective to bind him to and that makes him difficult to relate to. Also some overacting occurs.
Anyways, I respect this. Good job.