Have to say, it's a nice throwback to some of the earlier styles of blogging. The short, sharp posts are good for the realism factor (because most blog posts are, in reality, quite short, and not the length of a small novella). It feels a little...I don't want to say clichéd, because it isn't. Maybe too trope heavy (from the psychological reasoning of Slendy's appearence, to the random stranger who can also see what others can't seem to). That's probably also not quite right, but as close as I can get to at the moment. I wouldn't say it's entirely realistic, but it could fool some people.
I will definitely keep an eye on it though, as it is a nice change of pace from the arc/crossover/continuity heavy blogs.