I spent a couple of winter nights in while in the forests of Northern Arizona. The bivy kept me warm and dry in the snow. When sleeping that first night outside, I always end up tossing and turning, the bivy was nice and roomy to let me move around (I'm 5'9" and wear a L jacket). The only thing I don't like are the fifty-thousand (i kid) zipper pulls. Granted they're all labeled, but at 2 in the morning, I'm not looking to read the label.