It's a charter school. That means you don't have the luxury of... say... full time janitors. Everyone does everything. Also, the equipment and facilities aren't always what you need them to be. Although I'm listing this as a Con, it's part of the experience of doing more with less.
Also, if you're from a public school you might find the fact that you can be fired if you don't perform as a Con. Obviously, if that's the case, you're not of the mindset to work in any charter school.