This bed is definitely super comfortable. I bought a 3 inch mattress topper to put on top of this one, but it didn’t even need it. 
I will say, the reason I gave it only 4 stars is due to the fact that around the edges and corners, the mattress never took “full form”. 
We are renovating the other half of our whole upstairs, so I’ve had this mattress unboxed and laid out for over a month(No bedding or anything on it weighing it down).  It’s had more than enough time to take form as it was supposed to.  The corners still have a slight sag to them, as if the mattress is frowning. It’s not visually noticeable now that I have all the bedding put onto it, but you can certainly notice it when you’re getting out of bed, especially at the foot of the mattress. You basically slide off. 
I could’ve received a one off mattress, and had it not been for those corners, this mattress would certainly be 5 stars! I love everything else about it.