The first night I slept on this mattress I woke up with my back hurting, but every night since then, my husband and I have both slept great.  We really like it.  I'm thinking I had overworked my back the weekend prior to sleeping on this mattress for the first time and that's why I woke up with a back ache.  Anyway, it only happened that one night.  The mattress arrived in great condition and was pretty easy to handle even though it was king sized.