Terrible Pay, frequent change and movement in leadership/management, bad politics/hypocrisy, poor communication/disconnect from corporate, rapid growth, low teacher retention, long evaluations during breaks.
As other reviewers have mentioned, they focus on hiring fresh grads from liberal arts schools. Although I like that they are finding experts in their subject/field, they also need to invest time to train them how to teach! Many of the teachers I have come across had great intentions and were very knowledgeable, but were unsuccessful due to the lack of training and unrealistic expectations from the organization.
If you ever decide to e-mail corporate, don't expect a response. The only time you see or hear from them is when they come into your classroom twice a year with long yellow notepads, a pen, and a scowl.