My six year old  son loves this bed. We currently do not have it fastened to the wall and it is pretty sturdy even when I climb up there.  It would be nice if the bed railing was a couple inches higher. We do have a standard sized thickness mattress (11-12") and the rail comes up just 2-3 inches. It is more than enough to prevent even an adult to roll off but it would have been nice if it was a little higher. If you went with a 9" mattress the rail would be plenty high.