Robin, I serve on the board of a charter school. Melissa is correct that they vary widely. Because of that I cannot say whether I am a fan of them or not, as a rule. They can be somewhat controversial since they get public funding, just like public schools, which means they arguably pull funding from other public schools. Public schools tend to be of the opinion that Charter schools are poorly run, not needed and a drain on public school funding.

Charter schools must be "approved" (usually by either the school district or the state).
In our state, charters were approved by the local school district, and because of that few were ever "approved." Recently, they changed the law to allow them to be chartered through the state, which has resulted in more schools being approved.

The Charter for a school must demonstrate it is meeting some "need" not met by the public school, must have proper bylaws, budgeting, a proper board, etc. For example, in our city, there are charter schools integrating deaf/hearing students and teaching sign language as a second language; emphasizing the suzuki method of teaching and music; international studies and foreign languages; sciences; and performance art. The school I am on the board of is in a low socio economic area and is focused on reengaging dropouts frmo the huispanic community to get them involved in Architecture, Contrcution and Engineering, and is closely partnered with our Association of General Contractors to prepare them for engineering degrees or positions. Charter schools are open to the public, in other words, anyone can enroll, and if there are more kids who want to go than spaces, they are placed on a lottery. Because of the various focuses, some schools are harder to lottery into than others. Then there are issues like transportation, small class sizes (and therefore, small number of faculty), etc.

But, that being said, a well run school is hard work, and there are lots of charter schools that are started by a parent or parent group that may feel their child is not being served by the public schools, but are not really prepared to meet all of the reporting and academic and financial needs of running a school. The Charter I am involved with has an Executive director with many years of academic experience, a board that is served by experienced professionals in the accounting, contruction and education fields, and is lucky to have an extremely motivated and experienced faculty. It takes years to get "up and running" and people must be willing to work toward that for a school to remain succesful. Many do not unfortunately.

I personally would not send my child to a "startup" charter school, as I would want to see a proven record of success, stability in the leadership, and the "culture" of the school that has emerged to see whether it is a good fit for my kid. 

Travis taught at one, and help begin another in Ohio.

His had a special niche though, and as such, the topic is a huge hot topic for him.  Let's all just be happy he doesn't hang out here, lmao.

He worked with kids in the 1st who were sexually aggressive (victimized other children, most recovering victims themselves, though a few sociopaths).

In the 2nd, these were kids the court ordered out of the home and into a group home for continued drug use, and other significant issues.  They were a challenge in the public school because they would be sober at the group home, then see their dealers (or be the dealers) in the school setting.  They asked Travis to begin an in-house charter school for those students.

Why the hot topic?  Politicians are sometimes very quick to point to testing statistics as to why charter schools should not exist.  They are typically the same, or in some cases, average as a whole lower than public schools.  What people often don't understand is that there are some schools that completely skew the average (like Travis's kids).  Did his schools take money away from public education?  You bet.  Did you want his kids studying next to yours?  I absolutely promise you did not.  Horror stories, seriously.

That isn't all charter schools.  I know there are wonderful ones (my friend has had her son on the waitlist of one for three years, it is an art-based program.  They were 70+ on the waitlist this year :(  ).  They range so widely.  Here in Maine, they were illegal until this year.  They are allowing a small trial number.  The first is an agricultural high school that bases all curriculum on developing farms, etc.  It is actually pretty neat, and meets an important population.  Too early to know the stats on Maine though.