Nice idea. I like multiple exposures but I think maybe for the top shot I would have made the tree more prominent and had a lesser blend of the face. I think also I would have cropped into the face - not included the shoulders and chest .Just a personal opinion though :-) Have a look at
http://www.uelsmann.net/. Jerry Uelsmann has created some amazing multiple exposures using negatives and it might give you some extra ideas.
Karen