We've had our Tempurpedic for over 7 years and I LOVE LOVE LOVE it!! I was pregnant when we got it and had terribly stiff joints and lots of pain in my hips when I slept. My first night on our Tempurpedic, I woke up pain-free in the morning and was ready to star in a t.v. commercial to sell these mattresses. We'll never buy a spring mattress again.
It did smell a bit when it was first here but we had it on our floor for a couple of weeks to "air out". We expedited this process by walking on it whenever we passed through the room (no shoes of course).
One of the best things about it is the way it absorbs motion. I'm a VERY light sleeper and since having our Tempurpedic, I no longer wake up every time DH rolls over during the night. It's so great. I'd highly recommend it.
When mattress shopping, we also looked at the Sleep Number bed. We didn't like that we could feel the frame going down the center of the bed. But my biggest problem was that I liked the mattress soft to lay on, but then it was too soft to sit on. I would have had to increase the firmness of the mattress to sit on the edge of the bed just to put on my socks. Kind of crazy and too much hassle.
The Tempurpedic felt very firm to me when we tried it at the store, but we had a 3-month money back guarantee so we bought it. I'm so glad we did!