The Zissou has been the darling of the outdoor industry press in 2012. The bag is one of the first of its kind to use chemically coated hydrophobic down that, according to Sierra Designs, stays drier longer, lofts better when wet, and dries faster than untreated down. Our testing- we slept out in the rain and in many wet environments- confirms that this is true, though the difference is much less significant than we anticipated. In our opinion, current DriDown is not yet the perfect hybrid of down and synthetic insulation; when wet it retains slightly more loft than traditional down, but it's not as warm as synthetic insulation when wet.
In our tests, we found the Zissou's 600-fill down was neither as compressible nor as light as higher fill powers. The bag weighs 40 ounces on our scale, making it a mere 4 ounces lighter than our top rated synthetic sleeping bag, but 15 ounces more than the Feathered Friends Hummingbird. In wet conditions we found the Zissou performs slightly better than a traditional down bag, but it weighs nearly 1 pound more than the top down bags, doesn't pack as small, and is made with lower quality fabrics. Going for $280 list, we believe the Zissou is a low value relative to alternatives and suggest- if you're psyched to try out this new technology- waiting for 800+ fill bags with hydrophobic coatings.
Quilt style sleeping bags are warmer for their weight, much more versatile, more comfortable in a wider variety of conditions, and lighter than traditional style sleeping bags with hoods and zippers. See ourBackpacking Sleeping Bag Review for all the details. If saving weight is a top concern see the Ultralight Sleeping Bag Review.