First, I'm a 6'1", 170 pound guy, a cold sleeper, and prefer to roll onto my side.
This bag replaced my 9 year-old Kelty Cayenne (+20F, Polarguard 3D) bag in 2008 after I woke up shivering despite a hat and thermal underwear on a trip to the Rockies the year before. This is my first down bag and so far I've not been disappointed. First, this is a seriously warm bag. Even when it got down to the mid-twenties at 12000 ft. in the Sierra I didn't need the hood; I didn't even need to zip the bag all the way up while wearing only boxers and a t-shirt. It compresses nicely into a medium eVent compression sack, and mine (a regular) could probably eke into a small with some patience. As many other reviewers have noted, the double zipper allows for venting on warmer nights. The draft collar has a watch/contact pouch and an easy to manipulate drawstring. I can easily roll onto my side and not get a draft even with the bag unzipped. My only complaint is that the drawstring and cordlock for the hood work their way behind my back or shoulder sometimes, and I wake up with an uncomfortable lump under me. That's the only bad thing I have to say about it; after three years of abuse it still lofts up nicely out of the compression sack, and has no signs of wear or loss of feathers. If you're a cold sleeper who likes some room to move, definitely give this bag a try!