Let's see.... Tempurpedic feels different because it's memory foam. It takes a few seconds for it to adjust to fit you after you move. It doesn't have an instant reaction like regular mattresses. So when you roll over, the curve of your body shape stays behind you for a few seconds and you sink back into the mattress again. It sinks slightly to fit you perfectly. We've had ours at least 5 years and it still springs back as soon as we get up or move.
One great thing about memory foam is that when one partner adjusts, the whole bed doesn't move. I love that. The bed only adjusts to the person who moves. I've slept on beds that would do the shimmy if one of us rolled over... no more!
On the sweating, your mileage may vary but we've never had a problem with that. Hubby and I are both hot sleepers and do fine. I have a thick regular mattress pad and cotton sheets on ours and don't sweat at all. I think laying right on top of the mattress would be sweaty, but with sheets etc. it works for us.
Maybe the prices have gone up since we got ours. But we didn't find it to be that expensive compared to the other mattresses in the store. There were many higher end mattresses from reputable brands that were twice the Tempurpedic price. Again, your mileage may vary.
Just a warning, if you get one you'll want to leave the windows open a bit for a few days. It does need to off-gas like other mattresses and ours was pretty smelly at first. Within a couple of weeks the smell was pretty much gone and it hasn't been a problem since.
