I have neither home-schooled nor been home-schooled, but I have had some exposure to the homeschooling circles in my area. (I worked for a homeschool curricula & resources distributor, several families in my church homeschool, my sister has homeschooled, and I work in a library where I've assisted a variety of homeschool groups.) Reading this thread has generated a number of unconnected responses.
1. I've seen a lot of homeschooling parents who put in serious effort. They research curricula to find the best fit, or they build individualized curricula based on pre-existing guidelines. They place multiple inter-library loans to get age-appropriate enrichment materials. They hold their children to high standards, and put a lot of time into prep, teaching, and testing, as well as various enrichment activities. On the other I have also seen one homeschooling parent who did not know the difference between an encyclopedia and a dictionary, and was not interested in finding out.
2. My exposure has mostly been to those who homeschool for religious reasons, and the more conservative among them seem to gravitate to curricula with a limited worldview and in some cases limited critical thinking skills. There are a number of private schools in my area that mostly consist of kids sitting at desks using this conservative curriculum, with an adult (usually 18-25) who may or may not have completed high school acting as teacher. This worries me.
3. There are a lot of excellent resources and curricula out there, though, and I wish that they had been available for my husband, who was exactly the wrong kind of temperament and skill sets for standard classroom education. I can't name names at this point, as it's been a few years since I worked at the distributors, but there were some great series on fostering critical thinking, grammar, foreign languages (including Latin, which intrigues me), and the like, in addition to the core maths, sciences, and English.
4. The library where I work hires high school students as assistants, and we do like hiring homeschoolers - the ones we've hired have been disciplined, well-read, polite, and their flexible schedules are a bonus.
5. Children will value what they see their parents value. One of the basic ideas of encouraging child literacy is to let your children see you reading - for yourself, not just to them. That conveys that reading is also an adult pursuit; it's not just picture books that you grow out of. In the same way, parents that value education by checking on what the kids are learning, keeping them accountable to finish their work, helping (or arranging help) where needed, will show the kids that this is important. While that might not pay off right away, long-term at least some of that attitude will stick.