I have had mine for about 3 months now. I am starting to love it, but it has taken time to adjust and I expected that.
First - if you do not like to be warm, forget about it. This is not a problem for me. I do wake up hot sometimes and throw the covers off. That said, I sleep alone because DH and I have different schedules. If we were sleeping together, I would have to have a king size or I would get too warm from him creating even more heat.
There is an odor which dissipates after awhile. Doesn't really bother me - I think all mattresses have a factory odor at first.
It does take some getting used to. The foam is pretty hard at first, but will gradually soften a bit over the first few weeks. Give it time if you don't like it right away. I sleep on my side and it was darn uncomfortable until the foam finally softened - a few weeks. On a side note - I was so out of alignment from my last bed that the tempur made me hurt even worse. I saw the chiropractor a few times and it is so, so much better. I do not have any pain or stiffness in the morning anymore caused by the bed.
Back sleepers should have an easier time learning to sleep on this type of mattress.
I believe in this case you do get what you pay for, and they have a great warranty. I wouldn't mess around with the non Tempur beds unless there was a really good warranty/return program from a company who has been around for a long time.