Wow! I love this blazer! I've been coveting it from afar since their release and I finally purchased it as a little birthday gift.
My measurements indicated i'm a "medium" but, I ordered the small (since the medium was out of stock) to try on while waiting for the medium to restock. The small fits very well and if I had gone up a size I would have been swimming in it!
The only thing I don't like is that the back vent is almost always completely splayed open. I really like the rest of the blazer itself however, so I might see what I can do to address that issue.