I agree with Reks about support, but I'd call it medium firm. I like a firm mattress and I loved this one. I thought the cool gel technology actually helped some as well. I hate being hot when I sleep.
All this said...It'll be about 30 days before your body fully adjusts to a MF mattress. Not that it'll suck before that, but after I had my first MF for about a month, I woke up one morning and realized I hadn't turned once all night (a minor miracle for me), and have absolutely loved them since.