I really like the way that you colored this; drawing by hand and coloring digitally is the way to go in my opinion. My only nitpick about the coloring is that it goes outside the lines sometimes, though that's very hard to avoid with paint (assuming you painted it with watercolor; it looks that way to me). A little bit of digital editing could easily fix that, though.

You also did a great job on his fingers; fingers are hard to draw, especially with nails like that.

Anatomy-wise, I think he still looks too much like regular Sonic (IMO it looks better that way) but his body as a werehog should be a bit bulkier, especially in the arms. I also think a background (probably a dark background, like purple or navy blue) would look much better than plain white and really would bring out the mood of the picture better.