B&W often fits urban scenes particularly well. By focusing on shapes and tones rather than color we are able to see more of the detail of the scene. In this case we have a main subject and then the strong leading lines of the fence/street taking us further into the image to the distant people. I think in this case it could have been even stronger if the musician was larger and there was less foreground to the image, placing the musician on the lower left intersection point of the rule of thirds grid would have added more impact. Still, the overall image is very good.
You can read the story behind the image on the original submission page.