Montrealerwrote a review of Black Diamond Spotlight Bivy on September 28, 2012
Familiarity: I've used it several times
This is a pretty good little bivy bag in most respects (lightweight, adequate headroom, ability to use only the bug mesh and therefore see the stars at night, etc.). However, a MAJOR problem is condensation; I had this out for three nights in great weather (no rain, around 8-10 C) and within hours each night my sleeping bag started getting damp, eventually getting quite wet by the morning. I dried the bag and bivy out each day, only to have the same thing happen again the following night. The problem is that the top of the bivy is right against the sleeping bag, so there is little breathability (imagine sleeping right up against the wall of a regular tent). Because of this, you'll be uncomfortable and will keep waking up regularly to change position in a futile attempt to stay dry.