Constructive criticism? That’s going to be tough, since there is very little that could make this fine job even better. That, and I’m out of my league with the sculpture, so my comments are going to be from a CG perspective. That said, here goes:
The modeling on the chair is absolutely awesome. It is totally ambiguous as to whether it was shaped to that design or the design was carved from the shape of something else. That gives a very alien feel to it.
The chair has exactly the same coloring as the alien, and looks like the same material. There’s an implication there that the alien canibalizes it’s own race for furnishings.
The alien is incredibly well modeled, with lots of great detail.
The sculpting implies an exoskeletal or scaly body type. especially around the eye. Which is great. But it’s also not carried to the rest of the body. That, in turn, emphasizes the similarity between his body material and the chair’s.
The skull is as well modeled as everything else. You’ve also fit the fingers to it perfectly.
Where are the skull seams? And the teeth should have a slightly enameled appearance.
That was as objective and fair as I could make it, Danny. Honestly, if you were to put it on display as a finished piece as it is, I would still hail it as a 10. You’ve done an excellent, excellent job – even if the background is all that’s ZBrush. Thank you for sharing!