The large upper body volume seems typical of Valandre's bags. I tried this bag, but found it to be much less warm than, for example, Nunatak's Alpinist, which is similar in price and total weight, though I think more lofty. The difference is that the Alpinist fits more snugly in the chest region. Excess volume in a bag, though it might allow one to wear a down jacket, also pretty much demands that one wear that jacket to avoid having to heat a volume of air which changes during the night every time one rolls over, because of the bellows effect.
I also felt that the available down, spread over the larger area required by the greater chest volume, developed cold spots.
For much less money, on sale, one can buy a North Face Beeline, which, though it has no zipper at all, uses Pertex Quantum and 900 fill down, and weighs 18.6 oz.