WE have had a Tempurpedic Mattress for 3 years. At first it was a little weird, but I noticed I wasn't waking up at night anymore, also felt alot better in the lower back after about a month. It is a frigid ice block if you keep your bedroom cool like we do, it doesn't take long to heat up though, as it does, you sink down in it. I like the tempurpedic pillows more than the bed to be honest, they are great for neck pain, and around $100 verses the $1300 we paid for the mattress.
Two things I don't like about it, a heated mattress pad or electric blanket will soften the foam and makes it feel like mushy when you get in at first. It isn't a permanent thing, just when the heated pads are turned on. Also it is about the most similar feeling of dragging a dead body around if you have to move it ever. I have never had a more cumbersome and heavy mattress.
For a long term report on ours, I would have to say we were happy wiht it for the first 1 1/2 years. After that, it began to not conform as well anymore and has gotten too soft for me to lie on at times. We have put in a complaint to the bed store we bought it from and Tempurpedic as well. Tempurpedic sent us a letter that told us to take pictures of any sunken regions of the foam and to lay the mattress on a solid hard floor with no bed base under it, then photograph the bare matress with a straight edge on it to show if it is defective. Up until this, we were happy with it. Now I am wondering if it was worth the money, the replacement procedure has been a real headache to say the least. We still have not heard from the store or Tempurpedic in 2 months as to what they're planning to do for us.
I have laid on brand new ones at the bed stores and it is completely different than ours in firmness and contour, which really bothers me after such a short time with ours. I expected it to be several years before seeing fatigue in the mattress. Ours is a queen size.