Avantages
They had a good system for teaching the lowest level maths (everything up to high school.) I learned a lot about how to communicate some of the fundamental ideas of mathematics. For high school mathematics, it was mostly taught from the text book of the student. The group format (multiple students per tutor) works very well.
Inconvénients
Low hourly wage compared to most tutoring programs. At the location(s) I worked, there was too much focus on route production of work. This is not always bad, but many of the younger students had a very hard time working 45 minutes straight, with full attention. At times I felt like I was instilling a dislike of mathematics to the younger students by having to push them to produce more work instead of letting them enjoy the activity of learning math.