My son went to Woodlands Montessori at 98 Repulse Bay for a few months last year, and took the bus to-from school. We chose it because it was close to our house and offered English/Putonghua. In reality, DS's Putonghua was much more advanced than the other students, and the Putonghua-speaking teacher, while pleasant was not the lead teacher so DS did not get much reinforcement of his language skills. But that is not the complaint.
His class had only 12 or so students and 4 teachers; in theory this is excellent. In reality, he came home three times with a cut lip, bruises or scratches, and although I asked the bus monitors (in person), and the teachers, no one was able to explain what happened. While I accept children have accidents and certainly don't blame anyone for that, I do expect that the adults in charge be somewhat aware of what the children are up to.
I visited and spent the better part of a morning with the class and saw that although there were four teachers, they could not even direct the children to the tables for special snacks. There were sharp voices and snatching (by the teacher!) DS was in a Montessori centre before we came to Hong Kong with a higher student:teacher ratio but a much more organised and calm environment. On the whole, I believe the philosophy is good, but what I have learned is not all Montessori classrooms are the same, and it depends very much on the teacher, much more so than in a 'traditional' classroom.
Also, a number of times, on other matters, I called and left messages that were not returned. We moved DS to a different, traditional school that is much more professionally run. To top it all off, it has been over a year, and Woodlands still owe us money.
YMMV