Generally looks pretty good, and the eyes are spot on. I really llike them.
But a few things could use attention.
First, the flag. Painting the stars and stripes is daunting and nearly impossible. Look to see if Archers Dry Transfers has a 48 star flag the right size. If not, do a search online and download an image to your computer. Import it to word as you would clip art. Resize as needed and print in highest resolution. Attch it with thinned white glue. That will look a lot better.
Second, the white spade on the helmet looks like it was painted over the netting. Carefully retouch netting where it's white.
Third, maybe the jacket highlights are a bit too pronounced, but the jacket looks like leather. In fact, if this WERE a leather jacket you would have nailed it.
The face is a bit monochromatic in the pictures, except for the five o'clock shadow. Try emphasizing the frown line by the nose. Go maybe a shade darker on the base flesh then bring up a highlight on the cheekbone. Add a touch of dark flesh/brown in the nostrils. Before adding the beard, try getting a bit more highlight on the upper lip, jaw line and chin.
Hope this helps.