A great place for beginning teachers to gain valuable experience and training
Pros
Mastery is a great place for new teachers to "refine their craft" to be supported in working to become better and more effective teachers. I have been told in interviews, that many principals value teachers from Mastery because of the intensive supports they receive, and because they realize that these teachers generally can be better teachers than their peers.
Cons
What comes alone with the support that is offered to new teachers, is that there can be a level of stress having supervisors, coaches, people from the central office frequently in and out of your room giving critique constantly. If you are someone who uses this to become better it can be helpful, if you are someone who has a hard time taking constructive criticism, this may not be the place for you. As compared to other district jobs, the pay can be better, but expect to work for it. The mandated hours are longer (by up to an hour a day) plus Mastery requires its teachers to work far more days each year, and offers fewer PTO (7 Days) as compared to around 14 days for most districts in the same geographic area.