I've been using this mattress for about two weeks now and it's decent. It's on the firm side when comparing to my previous mattress which was rated medium. It's very soft and gives in when you sit on the edges (which is not normally recommended) but very sturdy when you are in the middle.
I did feel some aches and pains for a few nights as it is much firmer than what I was used to. If you are a side sleeper it's probably not for you. Perfect for those who sleep on the back with great support. I feel a bit uncomfortable when sleep on my side given the level of firmness.