I think it came out really well! It really looks great. I don't really have much to say. I see some little differences in proportions and angles on certain things, but I don't think it's a problem as its only noticeable because the photo is next to it and none of those differences look wrong.
So really my only possible suggestion to maybe enhance this already nice study, would be to pick a focal point you really want the viewers to look at and make things go progressively darker as they go away from it, a little bit like there was a stronger light on the fical point you chose. It can be subtle, but I think it could be a small touch to enhance the composition even it's different from the original photo.
I hope you wont mind my little paintover, but here's a quick little example I did using the cats as a focal point, as they're the obvious one in my opinion.
As I said it's just a suggestion. It's up to you to decide if you'd like to try it or not. The painting is already real good as is. Either way, keep it up 
