There is something both amusing and horrifying about this piece. It's a fascinating mix and you've done it really well here. I particularly like the way you've combined vibrant colors (like those oranges) with dark, somber colors (like those grays/browns).
I think that the rain is a cool effect, but the splashes in the puddle look a bit too forced. Part of it is that they're all lined up, when rain falls more randomly, and the other part is that the ripples don't overlap, which they generally would. If you could adjust that to look more natural, it would also help with the perspective a lot.
The message here is pretty powerful; I said it was amusing, because of the way you've got the Spare Change sign (with a backwards G) and the fact that it's still out there when the guy is not. But it's really more horrifying and sad when you think about some poor homeless person dying out in the street because they can't get any spare change or out of the rain. Great job combining those two--keep up the good work!