Honestly, best purchase I've made in a very, very long time. For context, I'm 6ft6" and my partner is 5ft4". We were sharing a 4ft double mattress for over a year (yes, I know)... We both constantly felt groggy and achey and never had a good night sleep.
We bought this King Size mattress and bed frame from Dreams in the sale and received both items about 6 weeks later. The bed frame was easy to build and very sturdy. The mattress itself did feel quite firm, but after our first night sleep we realised just how much of a difference a good quality mattress can make. My smart watch sleep tracker showed me that with the new mattress I was getting 80-90% deep sleep, where as before it was around 40-50%.
When at work and doing the day-to-day I feel far more energised and now we both actually want to lay in bed together and watch TV on those Sunday mornings. As a tall guy, I have enough room that my feet don't hang off the bed and it gives my whole body support.
Sorry for the lengthy read, but seriously.. try this mattress out.