I feel like you could have pushed your darks and lights a bit further though. One way to do this is to use a black colour pencil, and just put a few layers on. When you think its getting to dark, make it darker. That's the only way to really get those realistic values! And for highlights, something I hear a lot of traditional artists use for highlights is gouache. Its a very thick white paint which is suppose to be excellent for making highlights and really pushing the whites in your image!
Also, I think making the background darker, like in the reference image would have improved the piece. This is because the leopard is quite light in value, so having a dark background rather than light would make the drawing "pop" a bit more.
Other than those few things, I feel you did an excellent job with this piece! You're rendering technique is my favorite aspect of the image, and you were able to capture the fur texture very well. Keep up the good work!
Wraeclast's critique may be good advice, IF the effects described are the ones you wanted. But keep in mind that's a matter of taste ... to me, it looks perfect as it is. The soft colors seem fitting for a shy, soft-furred animal, who looks very animate and "present".
Ever wanted to know how to draw animals like you.. Very impressive Mother of god