I searched long and hard for a down bag with a water proof outer shell. I also needed a really warm one for winter camping. I love Mountain Hardwear and was determined to get this bag when I found it. My first night in it (well below freezing, but probably not -20) I didn't sleep as warm as I was hoping, waking several times close to shivering. Since that first night I have slept below freezing several times and have been warm in it. Last trip was right around freezing and I had to unzip it to let some cool air in. In the morning I checked my watch thermometer and it read 90 degrees (of course that is on my wrist also). I has sprinkled on my a little and the bag shed the water right off. Big negative- the zippers suck! it is difficult to move the zippers up and down and the bag often catches in the zipper. The head compartment is also different (smaller) than most bags that I am used to (can't add clothing to make a pillow). Pluses- down bag that compresses and sheds water. Final- good bag and hate the zipper.