Very comfortable.  I allowed the mattress to breath for 48 hours but it never came up to 10 inches in thickness.  It was about 8.5 inches but I didn't feel that was a problem.  I did put a pillow top mattress cover on it to make it more plush though and I slept on it for two nights and felt it was very comfortable so there are no regrets.  It's in a guest room and  does not get a lot of use so I felt it was a very good choice.