Haven't had a chance to use it, but I question the "breath-ability". The material feels much more nylon/plasticky than I would prefer. I got it in and immediately felt hot and stifled. I alos have a mil-spec gore-tex bivy to compare with and it feels much more airy than the storm bivy. The storm bivy is much lighter/compact than gore-tex so you have a trade-off/price to decide. I would not pay full-price for the storm bivy.
This review was written in the old system and had content requirements that are different than reviews written today.