The mission of the public school is to provide each student a Free and Appropriate Public Education. Appropriate is considered "grade level" progress in most instances.

Under this definition, public schools are successful with the majority of students. But, sadly, many students such as those with disabilities or those in lower income areas are left behind.

If success is defined by providing an education that helps each student reach their potential, again, schools fall short with certain groups.

If success is defined by providing a sound foundation for higher education, I think schools do a reasonable job of this - with average kids (those neuro typical, middle to upper middle class kids within the 25th -75th percentile). Outside of this "norm" they are less successful.

I think it is difficult to be all things to all people.

I like the word effective but most people define that - or try to - in terms of what's learned in school. My second point would be that it remains very difficult to actually measure learning. The idea that we can measure learning exists more because it comforts people to think so than because we've found a good way to measure learning.
My first point would be that most often we don't consider the first way in which any school should be effective - it should be safe. In the post-industrial world, children need a place to be every day - particularly so if both of their parents are working outside the home. For most of time, children worked alongside their parents in the fields - or in factories - but having appropriately banned child labor in our country, our children need a safe place to be while their parents labor.
Thus far we don't even try to measure that. Are our public schools effectively providing a safe place for children to be every day? And do we offer parents and the community effective channels to communicate their answers to that question?
That asked and left unanswered, we'd have to ask - what are the goals of public education? We can't determine whether it's effective without knowing what else it's supposed to accomplish. None of those impossibly long lists of standards can constitute focused goals - no one can read those lengthy lists much less teach to all of them.
My answer would be - any school that has a high drop out rate - the proof is in the pudding - it's not an effective school. If it can't keep student interest - then it's not operating in an effective way. I recognize there are Great challenges but the harsh point remains that if students are dropping out - the school isn't effective.
I dislike the idea of looking at SAT/ACT scores as a measure of effectiveness. The truth is - we don't have an effective way of measuring the effectiveness of schools so responses to your qood question will be largely anecdotal.
But as another person who's been passionate about education, I'll read the responses with great interest. Good luck with your book.