Brian J.wrote a review of Adventure Medical Heatsheets Survival Blanket Two Person on January 10, 2012
First, you never want to HAVE to use one of these but if you ever do, they are very good at keeping you warm.
The size is nice. I've used the smaller blankets before and having the larger just makes it easier to wrap yourself up if you need to. I suppose you could fit 2 people in one(like the picture) but I'm 6ft 200 pounds and I think it would be really hard to have 2 people in one.
Other than that, it is pretty much your typical foil survival blanket that keeps you warm when you need to be.