The thing about doing art is you can improve on a photo, it doesn't have to be an accurate tracing! I would also lighten up the are a bit more on the right side of his face, the shadow is again very dark, and makes that side of his face look a bit too narrow. All in all, though, it's good, and you did a great job on the eyes, which are so recognizably his!

And just saying folks, when you get used to it, using a mouse is no more difficult than using a pencil, and you actually have even more control than a paintbrush, as a paintbrush has neither an "undo" button, or a "save as" feature!