Can you drop a backdrop in? A sky sphere or even a 2d bitmap.
It's really difficult to get a feel for the lighting when floating in a void.
I really like the little details in the mesh, but the lighting just feels ... I don't know if there is a word for it ... flat maybe, or woolly.
It's nice, don't get me wrong.
Games coding is half artistic expression and half science, so feel free to tell me to Foxtrot Oscar if it's looking great to you, but to me it's just not quite 'right'.
A backdrop might help to get a better impression of what it would look like in a game.