Great looking jacket
This is one sharp looking jacket. The fit is only waist length and the wrist might be a little tight if you are a big fellow. I am 170 lbs 5'7" and the medium fits fine. The jacket is warm enough down to the 40s with a long sleeve T. No room for layering so if you want multiple layers go one size up. Wind block is excellent, I wear this to run when the weather gets cool and it is very comfortable.

Great all around jacket
I have owned several Arc'Teryx products and this has to be one of the best. Great athletic fit, technically very functional, and a good balance of warmth, wind resistance, and light weight. If you're looking for a stand-alone warm jacket this might not be your best choice, but it's very good at what it's intended for - technical mountaineering. Like all Arc'teryx products it's very pricey. Is it worth the price? Only you can be the judge. As for me, the great fit and functionality help me get over the price issue.

A great jacket
The Gamma MX jacket is all that it is advertised. The fit is perfect and sleek. The price is a litle high but the quality seems to be there. I would recommend the jacket without reservation.

high price - excellent performance
This jacket is a typical Arcteryx product: high price but you get your moneys worth! It is quite lightweight and fits nicely (it runs a bit on the smaller side - L is perfect for 5'10" and 180lb). It will protect you from wind and rain in moderate temperature. I like the high collar and the reinforced left front pocket.

Gamma Jacket is Great
I heard a lot of great things about the Arc'Teryx Gamma jacket and it has lived up to those expectations. It is not intended to be a hard shell or to protect you from harsh weather but to be a comfortable and light Fall zip up -- or mid layer. The quality is top notch, as you would expect from Arc'Teryx. The size is athletic so, be mindful of that before purchasing.