I thought you did a great job on this game, it was fun and I really liked the concept. I also thought the ghost levels looked especially nice and I liked the colours you used. Well done for sticking to the theme :D
My two cents - I think because the human character can jump but the ghost can't it feels like it's missing the ghost's jump mechanic, whereas if both couldn't jump it wouldn't feel like anything was missing. Other than that and the sfx/music (as others have mentioned) I think this is a really great game with a lot of potential! :)