Please note that I do not consider all of these negative things, yet others may do so. I am admittedly "bought in" to Mastery, but have tried to represent fairly what some may consider cons. Readers must consider what is it is that they are looking for in a particular situation and how well-aligned their goals are with Mastery.
--Mastery is intense. There is not a very strong work/life balance. Teachers who do well, especially brand new teachers, seem to commit all their time and energy to the job. It's part of the great thing about Mastery--everyone who works there is competent and hard working--but also puts a lot of competitive pressure on educators. This is especially true for beginning teachers.
--Mastery measures the rate of student success by performance on the standardized state-wide test, the PSSA. While there has been remarkable success with students at turnover schools in this area, if you're looking for a job that goes leaps and bounds beyond standardized test prep (focus and emphasis on the arts, sciences, inquisitive based learning, etc.), and lets you be as creative as you want in the classroom, Mastery is not there yet.
--Campuses vary a good deal; I'm extremely satisfied at the campus I teach at, yet I know morale can be lower or higher at others. Some have criticized the "cult-like" atmosphere and effect of Mastery. (Although to push back on this, I truly love working in an environment where teachers are generally all bought in and working to change the atmosphere of schools in the city.)
--Not exactly a con, but some might consider it so: the benefit of working at a place with very competent people is that if you are NOT competent, you are quickly weeded out. I see this as a benefit, since in public urban school districts, bad, tenured teachers stick around forever. This system prevents that from ever happening. But occasionally this negatively impacts a brand new teacher who is struggling and has room for growth to be successful. A good deal of support is offered to all teachers, but teachers who don't show adequate growth quickly go down the route of improvement plans followed by non-contract renewals. Mastery offers only yearly contracts, which some might see as a negative, but if you ARE one of these struggling teachers, it is nice to have a non-renewal of contract rather than a dismissal.
--Mastery does an AMAZING job at managing discipline and culture in the school, but it's still a school! The kids in these schools are still kids, and when you consider the average socioeconomic background of the students Mastery serves, the issues facing children in urban, low-income areas, and the previous schools these students have attended, you realize that they bring a lot of their own issues into the classroom. Some think of Mastery as a school that churns out robotically behaving students who keep their hands folded at all times and walk silently in halls. Not actually the case--the kids do misbehave, and strong classroom management is needed to keep control. Don't expect the kind of behavior and attitudes you'd find in a private school or public suburban school. (Once again--not a con exactly, but if that's what you're looking for, you should be aware)
