We bought this for our young daughter who was moving out of her toddler bed. It is beautiful and my children love having sleep overs with the trundle. I also like pulling the trundle out at night for her  in case she falls out, for a soft landing. I have laid in it and don't think this would be very comfortable for a full size adult to sleep in every night just because of the twin size. It also is high so if you want it for a small child, you might want to have a stool so they can climb in easier. Mattress size - 9" on top and 8" on bottom.