I really like this model. I find grey to be somewhat difficult to highlight but you nailed it, and the freehand is really good I wish my freehand looked that clean,, mine always looks uneven when using multiple colors. The one suggestion I would make is the exhausts or whatever you would call them, I can see what you are going for with the black but it looks like maybe you tried to drybrush with to much paint on the brush. Besides that minor detail I think the model looks great.
Also, is the writing on the front freehand as well?