I think you've done very well to get the black guy in such sharp focus given the very limited DOF and moderate shutter speed, as is shown by the fact that other figures close to him - both in front and behind, are quite blurred. The little girl in the foreground is blurred to just the right amount to not detract from the main figure - the black, guy - but is still distinct enough to figure very strongly in the shot.
The black guy looking at the camera and no doubt wondering why you've singled him out, really makes the shot quite powerful. A bit ruthless I suppose, but it's what good candid/street photography is all about. Is the little girl also looking at the camera? I can't decide, but her wistful expression contrasts strongly with the even stare of the black guy.
I'm not a big fan of mixed B&W/colour shots, but this one works really well and I can see the reasoning behind it.
