Let's get this thread back on topic.
As a portrait artist, the thing that stands out most to me with the unmasked head is definitely the mouth, specifically the way his over-bite is sculpted. A lot of people do have their top teeth falling over their bottom teeth when their mouth is closed. And when the bottom lip opens to show that, it is sculpted that way; but only from the front. The side view makes it look like his lower jaw is sticking out instead. That can't happen. I think if it were corrected, that might help his expression some. But I agree with others that his eyes don't fully match the expression his mouth is making.
I really like this new sculptor KA Kim, especially her Peter Parker. But Cap's expression needs a little work.