I think the composition here is pretty good, however I would have given it a higher rating if there were less motion blur (perhaps a tripod would help here, though I know that isn't always convenient and you already probably know that). But besides the shake, a good photo.
A lot of both implied and actual lines here, and I like the composition, but the over-exposure and camera shake (motion blur/focus), really take away from the strengths for me. I suppose it's hard to get no camera shake with an obviously long exposure (although I think you could have probably dropped the exposure significantly), while a train is rumbling by.
I've a whole load of six's to comment on and couldn't wait to get to this one, I like it a lot, but, it could have been a 7, 8 or even a 9 for me. Its obviously a long exposure to get the movement of the train and the people. But do the sign and the seated people have a double image? If it intentional, it doesn't work for me. If its camera shake then you should have used something to steady the camera. Having those sharp would have made a much much better image in my opinion. I have given it a six and I still like it.
Cool picture. Somebody's in London. :) I wanna go there again. I only wish there wasn't camera shake (the ground/wall/other static objects are blurred a bit because of it). The train is a nice blur though.