It's tricky taking pictures of the dark - they tend to turn out either black or blurry :) This is the view outside this evening...(Not one of my more inspired shots, but it's been a busy day!)
I had a couple silhouettes like this too but went with the shot from the ride home on Friday instead. I like the way the sky is a deep midnight blue and the horizon is almost black. I think you captured the way dark descends on the world in a good way!
You got a sharp picture and some detail of the clouds. It is a bit eerie.