I think in the long run, homeschooling is bad. That's not to say it can't have positive effects, but I think the negatives outweigh them in the longrun. Not just from the basis of socialization. I think the lack of academic diversity is also a negative in the longrun. It's not something we'll see over a course of 10-20 years, but over several lifetimes.
Homeschool kids do tend to test well, but many are economically well off combined with the fact that parents tend to have 1 or 2 students vs teachers who have 20+ students per class, and obviously parental involvement in homeschooling is much higher than parental involvement in public schooling. These factors tend to play a bigger part in why homeshcooling does well, less so than failures on the part of public schooling.