We don't have kids, but Karma and I have had a lot of in depth talks about this, for our if maybe one day kids.
Mostly for all the reasons already stated.
American schools suck. And a lot of it isn't the teachers, it's the polotics they are forced to play in order to keep a job. My sister in law was a teacher at a last chance school for toubled kids, and she quit because she was spending more time there than with her own daughter and not getting paid for the majority of the time she put in. She loved the kids and cared so much about their success, but she wasn't given the tools needed to provide what they needed. When she realized how much she was paying out of pocket, it just didn't make sense for her to stay in a no win situation.
Karma and I both had problems with school because we weren't challenged, so we gave up.
I like the idea of homeschooling because I can provide one on one attention. If they need more help on one thing, but a more accelerated plan for something else, I can do that. I can take them places and show them how what they're learning applies to real life.
Socializing is a big issue for us. I went to a very open, very arts enriched, very integrated school. We didn't have cliques. Sure people hung out with those they had things in common with, but many people hung out with people from different "groups".
Karma went to a school where there were cliques upon cliques, with lots cruelty going on in the halls.
I want my kids to have an open mind and judge people on who they are, not what color they are or religion they practice. Are they a good person? Great then why the hell does any of the rest matter?
So how do I provide that homeschooling? I've found plenty of groups to do that with. To do group field trips and whatever.
So in my opinion, homeschooling, at least in America, when done by parents who actualy care about their childs education, is a great thing.