I carried a nice 1/2 to 1/4 inch foam sleeping pad for years that barely even gave me enough room for my body. After a while of seeing tons of people carring a Therm-a-rest sleeping mat I finally bought one. Well actually two if that tells you anything.
I will be the first to admit that I do not like to pack something in my gear that weighs alot, hence the reason why the foam pad for so long. But once I noticed that peices of my pad where falling off due to it getting old I figured it was time for me to get something new.
The moment I laid down on the therm-a-rest I knew I was in heaven. I will never want to go back to the old foam pad again. Yes, I do still have it for keepsake reason I guess.
The therm-a-rest is diffinately light weight. I purchased the nicer longer ones since I am over six foot tall and the fact that they self inflate is even better. I can now use my breath for something more useful. Such as getting the camp fire built.