Yup, dragons are fun to draw.
Since they are imaginary critters, then one can't really crit the anatomy. I think if you made his front shoulders a little meatier he'd look a little tougher. The line of your wings get a little confusing. Where the one sticks out from behind his head, it almost looks like another horn and the top line of that wing runs very close to the neck... also creating another odd illusion. Still, I like his overall look. It must've took forever to do all those scales.
Here are a couple I did a year or so ago. Just the heads, and the "flames" are more place holders as they were (at the time) just possible candidates for part of a tattoo. (Not on me. Ouch.) I wasn't sure just what he wanted for a look in that department. Hopefully the dude has come to his senses and gotten a real artist to draw up something for him.