Some interesting quotes on unschooling from actual (or claim-to-be-actual) parents. Copied verbatim (with edits for length), punctuation/capitalization (errors and otherwise) and all.

They ranged from the vehemently outspoken...

Un-Schooling is for those parents who are LAZY and dont want to do anything. In my PHD studies at Arizona State we studied a lot of families... the parents were usually trying to compensate for their lack of being able to make it in society.

to the globally praising...

From what I've seen, these children will not only get into college, they'll do it at a younger age and graduate with honors. the somewhat illogical. Note that the point of unschooling is that students take charge of their own educations, including finding appropriate resources and mentors to draw upon. It is wholly possible to facilitate the learning of something you don't know.

There is NO good reason to homeschool or unschool your child. Are you a teacher, can you teach every subject?

And then the "social development" argument - because being limited to 15-minute recess arguments with children within a year of your own age prepares you to interact socially with the diverse range of people and situations that are actually out there in the rest of the world.

...will he be able to adjust well when he is finally presented to a group of people ? Will he be able to interact with them? socialise with them? mingle?

Not every approach works for every student. Unschooling isn't a magic pill that fixes all. At the same time, there are developmental milestones, and then there are human-imposed milestones; walking around one year of age is a developmental milestone (and even with that, there's a wide variation and they're all okay), but reading by age 5? That's all human-imposed. You're not "better" or "smarter" just because you can add earlier.

I think unschooling is a joke! I know a family that swears by it and their 12 year old could hardly read a simple 5 year old could read better!

It's strange how with just a few words I start drawing pictures of people in my mind; I should not jump to conclusions about how rigid their ideologies are, how they were raised, how they school their chlidren. I know mine are also biased, and it's always easier to see the mote in your brother's eye than the plank in your own.