This jacket defies easy comparison with most other down jackets only because it is so densely filled with down. If laid flat on the floor, the loft at the shoulder could easily measure 4-5", but that's only because the top and bottom aren't completely touching. Instead, they're held slightly apart by the firmness of the filled baffles and presumably by the differential cut. That's why I gave single-layer loft as a more useful measurement (I thought).
By comparison, the other down jackets I have (MH Ghost Whisperer, Montbell Mirage, and an older Marmot Plasma Sweater) seem loftier but less densely filled, if that makes sense. The Patagonia is undeniably warmer than any of them, with its generous insulation at the neck being a particular strength. As Brian wrote, perhaps Patagonia is testing the theory that down can be somewhat compressed (overstuffed) and provide increased warmth with less overall volume.