I think it is amazing. I personally know 3 unschooling parents. Their children are amazingly smart, social, independent, critical thinking, and very interested in learning. They take their children different places each day and use the questions their children ask as cues for what to teach them. One of their children starts college in the fall.
There are many misconceptions about unschooling. People think they don't get "taught" anything, that they don't get socialization, that the children just sit around all day. These misconceptions couldn't be further from the truth. Personally I wish I had the ability to unschool my children. Public schools are more about how to remember stuff for standardized testing than it is about actually learning.
If a child doesn't know how to tell time, as another answer mentions, that is not unschooling, that's lazy parenting. Almost all children mention time at some point in their toddler years and a good unschooling parent would use that time to explain how to read a clock.
I see the unschooled children and only see good things. Aren't we supposed to be raising responsible, critical thinking children who are prepared for real life? Unschooling does just that.