This sleeping bag is amazing! I've never had a down sleeping bag, but it works much better than the synthetics that I've had that have the same temp ratings. For me this is definitely not a zero degree bag, I am always cold though. I would say the comfort zone is about twenty degrees F while wearing a a base layer. I don't have a bag liner, but if I use a fleece blanket I don't need the base layers. I am 5'4" and about 125 lbs and I got the regular size. I wouldn't want to be any taller than that and try to use the regular, it it just about the perfect size. I'm a pretty petite woman so I can lay on my side in it with my knees mostly bent, but I can also just roll the whole sleeping bag over on the side with me. The zipper snags, but only as much as any other sleeping bag so it's not bad at all. The length of the zipper is really nice for someone who is always cold! When camping with my boyfriend I could never seem to stay warm even when cuddling, but now we can keep it unzipped to my hip and cuddle with a blanket over our upper half but still have my nice warm down bag covering most of my body. I haven't used it backpacking yet, but I did stuff it into my sleeping bag pouch in my pack and it fits very easily. The compression sack that the bag comes with is also great! The only pad I have used it with so far has been a Paco, so we will eventually see how it fairs when backpacking in the cold with a much smaller pad. The foot zipper is something I have yet to try out, I've been sleeping in about 30 degree weather so I've just kept the top unzipped a small bit. My feet never really seem to be very hot unless my core is overheated, so I don't think I will actually ever use this feature, but I see why it would be nice. My only complaint is that in my bag the down seems to have shifted away for the heels of my feet (if I am sleeping on my back), but it has been slightly like this since I received it. It has never seems to make much of a difference in keeping me warm so it's really no big deal. The down has not shifted in any other part of the bag. I would definitely recommend this bag!!!