I hated the Tempurpedic. It felt like I was laying on a mixture of sand and pudding. The guy at the store said that people either love them or hate them, there really is no in-between. We put out the money for a really nice, fairly firm pillow top mattress about 5 years ago, and it still is great. My husband has had several back surgeries, and he's done much better since we got this mattress.
Whatever you decide, make sure to get yourself a really nice pair of sheets with a high thread count if you don't have one already. We bought our first set of nice sheets when we got the mattress, and I think I spent about a month going to bed at 8, just because it was so amazingly comfortable.