Mike Haines wrote a review of Adventure Medical Thermal Bivvy on July 6, 2014
Familiarity: I've used it once or twice and have initial impressions
It's cheap, light, and waterproof. That's enough to make it worth bringing along as an emergency shelter. If your day hike turns into an unexpected overnight, especially if weather rolls in, this bivy could be a life saver. Make no mistake, though, it's not going to be a fun night. This bivy doesn't breathe, so you'll end up moist. It's also not comfortably warm below about 50 deegrees. But in above-freezing temperatures it's probably good enough to keep you alive until morning, and for the size/weight (maybe compare to a 20 oz coke) it'll have a spot in my day pack for longer hikes.
If I were buying again, I'd consider the newer "Escape" version that's supposed to breathe better. http://www.backcountry.com/adventure-medical-sol-escape-bivvy