Well, my experience with public education has been mostly positive.
Part of mine was as well. l learned how to spell, write, and read. I learned basic math. I learned various tidbits of history and science. This ended in Junior High School throught the end of High School, which was, for the most part, an utter waste of my time.
I'm sure there are inferior public school teachers, but, I hate to see public education criticized wholesale, because in my experience, it's not deserved.
Study the issue, look at the empirics. American kids on average are the most unaware, most unprepared, and intellectually shallow in the industrialized western nations. What's interesting is that American kids, on test after test in which their skills are matched against foreign kids, the American kids think they're very well educated and have done well on a test aganst their peers in other countries. When the reality manifests itself, shock sets in. American kids on average score high on self esteem, but low on tests of actual knowledge.
Any doubt here will be wiped away by a study of what American college students know, and the remedial education needed to get many of them to a point where they can make it through 100 level courses.
This should be of interest, as a tip of a long standing iceberg:
http://www.youtube.com/watch?v=Bx4pN-aiofw