I looks well painted. I think you need more definition between colors. Black lining or deeper shading in areas to make the different parts stand out better. The skull could benifit from a bit more shading an highlighting and horns are usually a different color that bone, fot a more realistic result make them darker brown or grey.
i like the NNM, but the skin could do with being a bit tidier and more 3-D, as could the yallow, try giving them a wash.
the armour could do with one last drybrush (i assume thats what you have done)
other than that a good solid mini
and i love the NNM - how did you do it????