Gimp suits aside, it wasn't the worst thing I've ever seen.
The "Monsters under the bed" narrative is pretty tired, as is the "shock" ending. I won't say anything about the acting as I've made short projects before and it's all part of the fun of making things like this; nobody is looking for Oscars.
I liked the sequence where he got attacked, it was quite trippy. The fetish suits were odd but kind of worked in acheieving a faceless, unknowable antagonist feel. The lack of action I'm assuming is due to the lack of budget, but the way he simply stands getting touched up really does seem like he's the belle of the ball at an S&M themed disco.
Relating to that point, is my main criticism. The almost unbroken use of still, face-level camera angles. The pan around the room at the beginning was good, but the camera being so still for the entire film killed any atmosphere. It makes it lose any sense of panic or urgency, and with that, any fright. The other points are about this specific film, so they're not of much use. This problem will kill any other project you make I'm afraid, so vary the camera angles!!
This is pretty minor, but since it doesn't seem like you're getting much detailed feedback I'll try and give you some more advice. A couple of things caught my attention that didn't really make sense.
- Danny responds in alarm to background music. An actual sound from within the room would've made more sense, but could've equally been unoriginal.
- The Shadow Man at the end is unaffected by the light. This wouldn't be an issue, as horror films often don't make sense. However, the light had proven to be a pretty major weakness during the main attack sequence. If they had simply not liked the light, it wouldn't matter so much.
All in all, despite my criticisms, it wasn't a bad film and the only point to improve upon that isn't specific to this film is the one regarding camera angles. Short films are very difficult as you don't have time to build any character depth.
Congrats on getting a project finished.
-Bizarre