I went to montessori school in 4th and 5th grades and really enjoyed it. Similar to 00:34, projects were normal and didn't phase me once I got to public middle school. As far as grammar goes, we arranged words on colored tiles that indicated the type of word. Articles were light blue, verbs were red, etc. It seems like a really simple activity, but I had a much better grasp compared to my middle school classmates. I'm sure we did other grammar-related things, but can't remember.
My mother always had to be needed, so she would tell me that I couldn't do basic tasks and "teach" me by making me watch her do it over and over again. Sometimes she would let me try and if I made one mistake, she would immediately tell me how she knew I was stupid and that I would always need her. I don't say that for a pity party, but to show that the montessori program gave me just enough independence, skills, and confidence to believe in myself. It's very possible that any teacher could have given me confidence, but seeing at 9 and 10 that I can plan my day, carry out the tasks, and do it well really shaped me.There was also a large focus in independence and the ability to really move at your own pace. If I wasn't understanding something quickly, it didn't stand out because everyone is working on something differently. I could take all of the time I needed. If I was really learning quickly, I could ask for more difficult work. It didn't depend on my classmates' speed.
My 3-year old is in a montessori program and it has been a great experience so far. He was originally in a federal daycare in DC and I do see the difference between his daycare friends and montessori friends. Similar to 02:16, my son and his M friends "host" each other. It's so cute at that age, especially when they eat. They use please and thank you, which kids learn in any environment, but they also set their table, serve each other, and then put the dishes away together. His M friends are also better about leading and following. I think this goes along with the mentoring that 02:16 mentioned. He is already "mentoring" his baby sister.

They're so young now, so it's hard to really say how it will influence him down the line.