Starting at a respectible 7.8 oz, this is a very interesting pad.
It's quite thick and was a good candidate for replacing my thermarest. I trimmed the length down to match that of the 3/4 length thermarest I was used to. This dropped the weight to 6.3 oz – less than half the weight of the thermarest.
Sleep-wise, I have only spent one night on it so far, and it was comfortable enough. I have seen other people recommend taking "Tylenol PM" at night to help get more rest – I might even try pairing those up too.
The biggest downside so far, is that it's bulkier in my pack than the thermarest. To the point where, I'm not sure if I can get 5-6 days of food in my pack anymore with this thing in it.
Order from Gossamer Gear, for about $30.
I ended up replacing this single pad for the a combination of the torso only pad version and cut down section of insulation pad. This was mostly due to the bulk issue. The two pad total less, coming in at 3.5 oz and 1.2 oz respectivley for a total of 4.7 oz.