I am 5' 9", 140 lbs. Bought the medium. Jacket was a little bulkier than i expected in the upper arms and shoulders, and overall, looser-fitting than i expected. I was hoping it would be more form-fitting... the small probably would have fit better. But, i still think it looks good.
The sleeve length is perfect, which is awesome as my sleeves are ALWAYS too short due to being tall.
Jacket is pretty comfortable, except that the collar can be a tad asphyxiating if not adjusted just right.
Most annoying thing is the cheap zipper. There is a velcro strap at the bottom of it, to protect it from tension when closed. But, if you forget to fasten the strap, the zipper pulls apart from the bottom rather easily.
All in all, a good jacket for the price.