At a state run school you at least know that the teacher has been trained and is credentialed. At a private school the teachers do not have to be credentialed at all. The main problem with state schools is funding.

I think that state schools are better preparatory institutions than private schools. I think that it's unnatural to separate boys and girls in to separate schools where they do not learn what it's like to intermingle with the opposite sex. Besides learning valuable social skills that will help them once they get in to the work environment, I think it's good for them to be exposed to people from varying socio-economic statuses to learn to work well with people from diverse backgrounds.