Generally, unschooling might work for the preschool and the early elementary age children. Beyond that age, there are things that have to be taught in order for the child to go on to college (hopefully, wishing one's child would become a college graduate is not against unschooling). The consequences of not learning to read or write or to know the multiplication tables cold etc are not as bad in elementary grade age they are at a higher age.
I have read a lot of unschooling blogs and articles out of curiosity - but, in my opinion, playing in the beach is not going to teach the physics of Force, Thrust, Acceleration and Motion and watching how a tree's branches grow is not going to teach calulus or geometry. And listening to a concert is not going to teach music skills or to drill them to perfection. (I highly recommend all these activities, but I like to call them "enrichment" and fun). I have seen a lot of people claim that they let their children learn only from their surroundings (by osmosis) as they explore and observe and they call it unschooling.
It will not work in the teen years or beyond - what a child needs is directed learning (it could be in the areas that they like), strong study skills (which have to be taught in my experience), executive functioning and a method to ensure that they do not have any gaps in their knowledge.
Unschooling will definitely not work in my family for sure.
