I have had this bag for about 5 years now and it has yet to let me down. The quality of manufacturing that Marmot put in this bag definitely shows. The bag packs into the supplied stuff sack really small and will fit just about anywhere in your pack. A really nice feature is the two styles of pull cords for the hood so you know whether you are pulling the bottom of the top when you want to cinch the bag right around your face. The down does not leak much, mine looks as puffy as the day I got it. The bag has a pocket by your face to stuff any essentials that you may need over night, this feature is really nice to put you watch into so you don't kick it to the end of the tent and miss getting up in the morning. The locking zipper is nice on the warm nights so you can just open the bag enough and not have to worry about it opening all the way while you roll around sleeping.
The bag seems to get stinky after a bit of use but it cleans up really nice.
Mountain Hardwear Piute is a similar style bag but usually going to cost you slightly more then this bag.