I like them, and I know they work to some extent, but I wouldn't call them a miracle or anything. I can wear them all day and still be comfortable, and every little bit helps. They have some cute styles now too, but they are so ridiculously priced. My DH bought me mine as a gift before the economy tanked.
I got a pair about 5 years ago and they truly helped my lower back pain. Unfortunately the way they are built you can't crouch down and put one bent foot behind you. I do this a million times a day (tying shoe laces, picking up toys, etc) and it was hard to remember not to do that (it breaks the plate of the inner shoe which is what makes them work). So they didn't last that long for me.