I have one and it gets used a lot. My daughter likes it on the high heat and will usually spend an hour on it. The first time she did it she was sweating a lot, but not much since, so I don't know what the deal is with that. I always fall asleep on it and feel better the rest of the day. The week I used it every day caused some herxing.
/www.crystalbiomat.com/information/60-day-trial/ This is the best trial period I saw. I emailed him with a couple of questions and he answered me pretty quick.
If I put a blanket over myself, I soak up more heat. We like them because we're not enclosed with heat building up around our heads.