Welcome aboard.
Good portraits have good lighting and you certainly have that here. It's relatively soft, but you've used a very deep ratio so it's quite dramatic. The lighting direction is also quite dramatic (from the side), that shows the texture and character of your father's skin. Maybe not the most 'flattering' light, but it's much more interesting than plain, flattering light.
I agree with ceejtank, there is too much dark background (dead space)...it doesn't seem to be adding anything or helping the image. A closer crop (probably vertical) would make it better.