i tried out the sky couch on a recent flight we were lucky and didn't have anyone in the middle so we just experimented with it
MrsWT73 really enjoyed it for relaxing. She is short- only 5ft 3inches. As a result, she can fold up her legs and curl up. Me at over 6ft 2 inches found it horribly compact and uncomfortable; it was too tight for my liking.
With a child, i would probably go PE.