We got Dawson's mattress up on his bed and put him up there to see what he thinks of it. He really seemed to like it, he was smiling and exploring. He learned he can touch the ceiling! He also learned that if he stands up and jumps on the bed, his head hits the ceiling pretty hard since it's only about 2 inches away from the ceiling to begin with! I didn't think he'd do it again, but he did the 2nd time I put him up there too.
Yep, he really likes it. :)