First few nights were not good. If you are moving from a traditional sprung mattress to the Octasmart, the difference takes a bit of getting used to. 
Having said that, I am now used to it (took a couple of weeks) and don't suffer so much with my back or neck as it provides better support and alignment. Leg cramp is also less of a problem.
I would recommend this product, indeed I already have, but just bear in mind that a better night's sleep doesn't start from day one.