I feel like this is one of your better pictures, my reasoning for that is, this picture explores more techniques that (as far as I know) you haven't really done and were well executed I might add. I definitely love your attention to detail, the face being more structured, the clothes having all these nice crease details, particularly on the pivot points/joints.

I know you said the speckling didn't quite give the effect you wanted, but I personally feel like it works really well. Certainly giving more detail and the illusion light is able to get through, as well as just adding some nice texturing. Plus from my experience with those kinds of glass windows, they to look a lot like this.

I think the circles idea made sense, I also think what you ended up going with looked neat, were the ones on the outer edge random? Or was their a logic in their designs? To me, it sort of looks like spell circles, it creates a nice effect, while fulfilling the purpose of having something to fill in.

You did really good, it's always a pleasure to see what you come up with.