Your dad looks awesome, and this is a great sketch! I wish that I had the patience to learn the skill of sketching realistic portraits, but all of my sketches are doodles :p
Lighting is very cool, and everything looks very well put together, but I have a question, because the thing is upside down: is that symbolic?
Either way, great teeth! Could be the start of a 1st rate logo, kind of reminds me of the brawny man.