I love the tone of this image, it feels nostalgic. I love how you drew screw loose, she still has her mangy fur but has a certain beauty to her without that creepy insane look. Like as if she's not completely crazy all the time, she's lovely. I also love how you have her howling at the moon from a rooftop. This is the best I've ever seen her portrayed and with such a lovely backdrop no less. Wonderful work here.
Even disheveled she looks so beautiful in the lovely moonlight, standing in such pretty pose and perfect placement. I like how you did the rooftops, and especially nice work on that lantern and hanger style. (The iron work in Ponyville is great.) The clouds, chimney smoke and overall hue make the scene more magical. It's nice to think she gets a chance to get out and be happy, even for just a night here and there.