there's nothing inherently wrong with charter schools. What is wrong is how politicians often stack the deck to make them more successful (or look more successful) than non-charter public schools, in order to further demonize the non-charter schools.
For example, they should be held to the exact same accountability standards as public schools. They should be made to share the load of educating disabled kids (not necessarily by enrolling them, but the amount they are paid per pupil should be less than the cost per pupil that the public schools pay which is skewed up by the requirement to educate disabled kids). They must pay their fair share of the cost of school bus transportation, which is a necessary part of compulsory public education. And when examining their results and comparing them to the public schools, the media and politicians have got to use apples to apples comparisons that adjust for the SES of the different student bodies.
Some charter schools are doing an excellent job and their methods can and should be scaled up. I highlighted some of them in the Success Stories thread, examples are more time in school, superior leadership, smaller size, and superior coaching and feedback to teachers from leadership.