As a bat costume, this is definitely a success. Great work. A bit unimaginative and vague, but somewhat identifiable as bat, nevertheless. Well done!
Outside of the bat context, however, I say this is quite unwearable a piece, even more so for something in the simple-black-dress category. (The model seems to agree; or is it just me who's reading confused desperation on their face?)
I imagine the length to be something to consider and to get paranoid about, and since velvet is heavy as hell, the vast, oversized sleeves would add to the inconvenience. I also don't find the shape of the sleeves very beautiful, but that's just a matter of aesthetics.
Spread your wings here. If you like bats and want to look like one, it could also be done more fashionably, I believe.