In general terms I really like the photograph, you can see, as you've mentioned, his inner workings trying to figure out what on earth is going on.I regards to the overall composure:
I like the fact that you've used a lower f/stop giving the subject more clarity, as it shows you've tried to capture his mood and expression, as opposed to the whole photograph of any happenings in the background.
However saying that, I do like the fact that I can still make out the bus in the background, it fits with the rest of the background giving the scene a somewhat busy feel, once again bringing more depth to the subjects expression.
Personally, I feel that if you could have positioned the subject just slightly more to the left it would have given him even more attention placing him across two of 4 crossover points when bringing into account the rule of thirds. Though you would have lost visibility of the space on the left of bus, which would have sadly taken it out of the photograph as your eyes wouldn't fix on it being so close to the edge!
I think you've done a fantastic job here In regards to the Black & White effect you've used
I do like black and white photographs however I've found that when converting colour to black and white you've also got to adjust all sorts of highlight, shadow and exposure levels, maybe even add a gradient map using black->white as the gradient as this will allow you to have much more control over these levels.
I really can't provide much more critique than that as I honestly think this photograph is great