Homeschooling put me far ahead of my peers. I went back for middle school (6th grade) and skated through the next 3 years until I could take AP classes in high school. I am by no means exceptional nor were my parents great teachers. I think being able to go at my own pace allowed me to learn faster and more thoroughly than if I had been in a classroom.

I'd say there are a lot of upsides to home schooling if parents can swing it, and the downsides can be mitigated by a little extra effort on socializing.