I have slept on my new mattress for 3 nights and I have slept better than I have in years. I'm waiting to see how it goes over time but I can't imagine that I won't feel the same way 100 days from now.
Because it's a good mattress at a good price and delivered in a convenient way. Only an 8 because my actual sleep comfort hasn't changed much. High quality product, but not revolutionary results.