Not good in the rain
Used this for a Wonderland Trail trip. Worked well until I experienced rain/snow the last night. I had my head under a friends tent vestibule so I didn't have to cover my face during the rain/ snow in hopes of reducing condensation inside the bivy, however, within about 30 minutes of getting into the bivy that night (rain was fairly heavy at that point) , the inside of the bivy was wet and my down bag was getting wet. I hadn't experienced any condensation the previous 5 nights, but that rain caused a lot of issues for this bivy. I would avoid this in rainy conditions and go with a Gore-Tex bivy.
Thom
Pennsylvania