Fun! Flying Stupid is right that the difficulty curve is a little odd, but the jumping felt good to me. The trail behind the character was nice.
While it is small and short (and quite possible to manipulate the bat's AI into a pretty early ending - not a bad thing imo), it feels complete enough for a jam submission. I also like how the game seamless blends into the jam page, small touch that helps.
Music was nice too!
Welcome to GWJ!