I was concerned about sizing on this. I ordered a medium. My son is a 40R, medium dress shirt, 5'11", 170 lbs, size 34 waist. Fit fine in the arms and overall length (just at bottom of waist), but the shoulders are a bit big. He has swimmer shoulders so he's not some narrow body type, but the shoulders are cut pretty full. If the sleeve length wasn't shorter, I might have been able to go with a small - bomber jackets are meant to be worn snugly, not oversized.
Jacket is heavy soft leather, feels pretty good. No bad odor. Probably a bit warm for California in the Spring/Summer but it will make a nice jacket for Fall/Winter in NorCal. He really liked it, just wished there were two interior pockets instead of the one.