Large and comfortable!
My husband and I upgraded from a Queen. 
This cake packaged in a box and very heavy. Once unboxed and unwrapped it sprung open and began expanding. We slept on it 6 hours after opening and it was comfortable. I tried to find online whether it was mandatory to wait 24-48 hours after unboxing and the general consensus was that it would not damage the mattress to use sooner, but it may not be to it’s full comfort potential until 24-48 hours have passed. 
We have been using it for a few weeks now and are loving it. Supportive but not too firm. My husband has a bad back and he has had no complaints over the past few weeks!