Great use of blur. I agree with Greg, the train was a bit difficult to discern at first. It took a few seconds before I realized it was there. The girl drew my attention so I didn't notice the train. That in itself is a very nice effect. I really like this photo. I bet you looked funny down low while taking this one. LOL
I love this shot. Terrific effect. The only thing that would make it better is if the train had been recognizable as such--a slightly faster shutter speed or a rear curtain flash perhaps. Great shot as it is though.