I've had one for about 3 1/2 years. I always caution people against buying one and here's why...it's what I call the tempur pedic curse....
As others have mentioned it takes a bit of getting used to, but once you do, that first 3 months with it is just like the infomercial...you'll feel like angels whispered you to sleep at night and wake up feeling great.
Then after that, you don't really notice it, which is the mark of a good bed; you go to bed, you wake up, and you're ready to go.
Where the curse comes into play is anytime you go away from your home. Doesn't matter if it's a nice hotel, or at a friend's house with a nice guest bed, you're going to wake up pissed off at the fact you weren't at home in your tempur pedic bed! You can take a great vacation, but in the end you're just going to wake up and say....I can't wait to get home and sleep in my bed!
So don't say I didn't warn you. My advice is to put a piece of plywood between your current mattress and box spring and get used to that. Then you'll be able to sleep anywhere and truly enjoy going places.