I made up a size 12 based on my chest measurement. I think the fit is perfect in the bodice, but the arms are a little firm. I'd like to make up this jacket again, perhaps in a cotton sateen, and I will sew the arm seams with smaller S/A around the biceps for some extra room. Fabric with a bit of give in it will also help.
I didn't adapt the pattern at all. I wanted to do the lovely cotton justice as I know I'll be getting lots of wear out of it so I bound most of the seam allowances with black bias binding. The construction of the jacket was super simple and it came together in about 4 distracted hours at the Mill Rose Sewaway. Of the four garments I started, this was the only garment I finished.
I love my new jacket and I can see more in my future, I might try the pattern without the ruffle as well. Stay tuned for my wearable muslin Roundtrip Dress.