Having no children myself, many will immediately not read this. So go past that right now.
On the other hand, I've had many, many, many friends who have debated this question, and many who have done it with extremely varying degrees of success.
Several friends took their kids out of the school system simply because the kids were .... well, what we'd call deliquent in another time. They simply could not get their children to get up in the morning and get to school, or when they did, the kids really didn't go to school, they disappeared. Some of these parents had a hard time getting their HS degrees themselves. In fact, all these kids (a half-dozen) wound up with GEDs eventually. THeir parents were not really prepared to home-school, although their intentions were in the right place.
A few took theirs out for religious reasons. I think you'd be better to send your kids to religious classes in addition to school, but then I'm a product of CCD, and like the little fish with feet. Most of these parents don't want their kids exposed to other religions and beliefs, afraid that they might fall prey to them.
Some parents took their kids out because they didn't think the school system was doing enough for their kids. I really wonder why they didn't think they could take their kids to the museum themselves after school hours? Or volunteer to take a group of kids somewhere.
It takes true dedication to home school kids, and usually parents do it for all the wrong reasons. In truth, I've not known too many who are real success stories. Few parents have the dedication to make sure their children are exposed to different cultures, to get them involved in athletic endeavors, to allow them to fail or succeed on their own merits.
In some cases, my friends' kids probably wouldn't have graduated at all, had their parents not home schooled them and managed a GED. So, they were right.
But the school system only gets worse and worse if you decide that the answer is to take your kid out of it and home school, when you could possibly work towards making your school system better.