It's suddenly hot outside, but I still want to wear this jacket!  I am 5' 6" and weigh 150 lbs.  I bought a large because I have 36DD chest, and the jacket zips up with lots of room, but the sleeves are very long.  I can relax and have the cuffs hang below my fingertips.  I would order a size medium if I were to order again.
The jacket has a fuzzy inner liner that looks like shortly shorn sheeps wool.  I like that it's not too thick (like Hollister/Abercrombie jackets) because they tend to make the jacket bulky.