The light underneath is a nice effect, and you've created lots of interesting shadows. The blown-out spots of light - especially on the top of the guys head, are a bit harsh, though.
I like it, but I think that the light or maybe it's the background makes the edges look a bit out of focus. It might also be a bit of dust (judging from the bottom surface), so perhaps getting rid of that might have helped make it have sharper edges.