This is one classy jacket. Its incredibly flattering, well cut, dare i say tailored? It has these amazing stretchy panels on the sides and underarms, and the cuffs are really well done. The thing feels better than a second skin. In spite of this, I returned it. why? well it's just so light weight I don't trust it to be warm enough all by it's onesies for 30 degrees and below. Maybe im just too used to my 5yr old 10lb north face gortex insulated number. Plus, I saw the Golite Reverb on sale for half the price and snatched that up. The reverb is sturdier looking and just feels tougher than the atom. By all accounts the atom lt is actualy very warm and sturdy, maybe I'm just not ready for the technology where such warmth comes from something so light weight, silky smooth, and attractive. If you get this (and i recommend you do if you have the dough), you should probably also have some sort of a fleece layer underneath for hellishly cold days. and as for sizing, I'm 5'8, 120 lbs with very long arms and broad shoulders, and the medium was roomy. I'd say you could size down on this one.