This is a joke in our family. Three years ago we stayed at the cabins and my parents were so miserable on the Murphy bed, they bought DVC for us all to share! My Dad likes to say that darn bed cost him over $20,000!
That said, the main problem with the bed was size, not quality. My parents are large people and my Dad is way over 6 feet tall. For a single adult, kids, or just smaller people, the Murphy bed would probably be fine, comparable to the pullout couches Disney has in DVC rooms... Nothing to write home about but not a vacation-buster, either. Overall the cabins are great and the many beds give you lots of choices about who GETS the Murphy bed!