Pros
This is a good opportunity for someone who is passionate about diversity in STEM and wants to engage in service during a life transition, for example between college and grad school, while changing careers, or after retiring. This is also a good opportunity for someone who is interested in teaching. The organization and curriculum are well organized. There is a good amount of training provided. While this program is not as well established as others of its kind (ex: Teach for America), it is continually improving and expanding across the country. Overall, it was a rewarding experience and I gained many soft skills (teamwork, mentoring, organization, etc) that are easily transferable to any job. I've talked about my experiences at Saga during many grad school and job interviews!
Cons
If you've never worked in a middle/high school before, you should know that the day to day can be quite frustrating. It requires lots of perseverance. You should also note that a person's experience is highly dependent on the specific school's team and culture (which I think accounts for some of the variability in reviews). Finally, there's not many opportunities for advancement within the organization and the compensation is terrible, which is why I feel it's best as a temporary job for those who love STEM and service.