That is pretty cool.
The way it is presented, it could almost be considered a sculptured relief, but essentially it's still a bust.
Do you have a photo of this before paints were applied? To me it seems his cheeks have been extended too close to his mouth. For a lot of the shadow lines, you are usually better off lightening the surrounding area, instead of applying a dark brown.
Historically, panzer troops would have the pink waffenfarbe around the shoulder straps as well. The headphones might be a bit too thick padded, but that depends on your reference.
Considering the medium you worked with, it's still pretty amazing what you ended up with.
regards,
Jack