My son went through Montessori from ages 2 until 11 (finished grade 5). As with any other institution, it depends on the quality of teachers. He had 1 great teacher, one good teach, and 1 not so good teacher during his schooling. There are a couple of key factors which made us choose Montessori:

- mixed aged group classrooms. So in one year of the 3 year cycle, he is the younger child (and receives mentorship from his older buddies), and in year 3 of each cycle, he is the older buddie mentoring younger pupils. Since he has no siblings, this is a benefit to his development.

- Montessori follow the state curriculum, however they allow children to manage their own time. So if he wants to do math all day, he can, and the teacher is there more for project management and giving him assistance than to drive him by a strict 45 minute schedule. At the end of the week, he is supposed to accomplish the assigned work (regardless of which order he wants to do it in). This will help him in the future with his own project management and prioritising work loads (we hope).

- the parents sending their kids to Montessori are not of the Elitist breed. I wont explain what I mean by that here. Its better than Steiner type schools (my personal opinion).

Other than the above, there wasn't anything particular about Montessori compared regular State run schools.