Working with Ken and Miki (Ken's wife - in my experience they work very much as a duo) was a great experience overall. They're both incredibly nice and professional. Communication in English was easy with Miki. Ken is very clearly a perfectionist - the initial measuring process was very thorough, and during the fittings he took a very methodical approach to correcting different aspects of the fit.
It's a medium-dark gray (lighter than charcoal) pinhead worsted - just a fabric he had in his shop that I picked. Nice medium weight fabric.
One other cool detail - I asked for Ken to make me a belt covered in the same fabric as the suit, after seeing the same thing on a suit he was wearing. Cloth on one side, leather on the other, really nicely finished.