This piece is so incredibly well-done, I'm not how 'worth it' it is to write the critique, but here goes!
I love the integration of colors - you've got a whole range of hues and shades, and yet it all works together seamlessly.
The lighting here is divine as well - some very bright spots, some rather shadowed, but overall a soft/muted and very smooth feel.
The dragon's pose is great, he certainly feels like a 'lord', exuding confidence and owning the area. I'm not a huge fan of the dark head or the lightning-bolt tail, but they're very impressive and well-done. My only actual critical comment about this entire piece is that the wings looks too big for the dragon - but that's it!
All in all, this is an incredible piece! I'm sure the commissioner was very happy with it