Seens you were really bad
There wasn't so much things to vary the sounds, to break the rhythm. That's good for an ambient song. But some beats were louder than others, making then kinda annoying after hearing then for some time.
It's still a nice music tough; the music gives a dark, gloomy atmosphere as you said and it's not something that gets boring too son (well, that's my opinion). A nice ambient song overall. Good job.