Love this.  Super comfy.  Obviously not a true stiff blazer, but it can pass - and it has plenty of elastic, which I'm thrilled about.  Great for conferences as a grad student.  I got a medium based off of recommendations, and it juuuust fit.  I'm 5'2 140, but I'm very pear shape, so I normally fit S/M as a top.  Definitely size up.