The cropped head does not detract from the picture at all. In fact its not a noticeable event. Why? Because of the balance of the image. you have you cropped at head and body and your moved to the left looking over the shoulder with more room to the right. Balance.
If cropped heads really bother you, they are pretty easy to fix, you just make the image taller fill in the extra amount with the background, bearing in mind where it is lighter and where it is darker, then crop part of a head from a different photo and place it where you want the top of the head to be, before making this an accomplished deal, be sure you colorize the new top to seamlessly fit with the old.
I use Adobe Photoshop for this, but there are other programs out there that can do the same thing.