I know a lot of homeschoolers who are now adults. They tend to think independently, work hard, and are... fine. One of them worked for NASA before choosing to be a stay-at-home mom. One is a pediatrician. One is an electrical engineer. The rest are similar-- well-adjusted, successful adults. They're all fine, if a bit socially awkward.

I think the socialization thing is probably the biggest drawback to homeschooling. It also probably depends entirely on the personality of the kids. Some kids thrive in huge group environments. Some don't. I guess it would also depend on how good and available your parent is, but most homeschoolers have very engaged parents from what I've seen.