Very good, voted. The face looks great, and that is the most important thing when doing a bust. To notch this up even further, take a look at Bailey's WIP and how he does faces by adding extra shades and colors to them.
The only thing I didn't like here, are the engravings on the red part of the armor. There's something about it that makes it seem wrong, as if you haven't highlighted it, but instead rely on natural shadow. I don't think it is what you have done, but it is wrong to my eyes somehow. Maybe this can be improved by adding some highlights.