its a good picture, it captures a moment but isn't a snap shot, hes not directly centered (good) he shows emotion (good) only thing that could have made this better, is if you were able to of gotten both hands fully in the shot.
The pic is not bad for practice. But your pic size is outrageous for those dimensions. 442 KB, and a png? You can optimize your web photos to be a fraction of this size and still have it look exactly the same as this in a jpeg.