Bought this on the cheap from SAC, and I'm happy I bought it, but happy I bought it for 60% off. As a pad, it does exactly what it's supposed to. I've stayed warm in a light bag down to about 45F, both in a tent and in an ENO hammock.
My only complaint is its size when packed. It's almost too bulky to fit in the pad straps on the bottom of my pack, and the width when rolled up is a bit cumbersome.
I'm 6'2", very athletic at 190 lbs. and I JUST fit. Anyone with a larger frame should definitely buy the XL version.
Overall, it's worth it (especially considering the price) to buy as long as you're not an ultra-light fanatic. I'm a big ALPS fan, and this is a solid product that will hold up well.