Absolutely. My girls were at a Montessori school in the UK and thrived there. The older one (8) is quite bright and has a real compulsion for learning. The younger one (5) is an August baby and so has always been a bit more immature than her peers. Looking for something similarly alternative and permissive, I signed them up for a 'progressive' school in the US at vast expense without actually visiting the campus. They assured me they could cater well for both.
They won me over with stories of how great they are at the arts. I also heard loads of great tales from parents.
Turns out, that's pretty much the sole focus of the school. One day, they had PE, double art and then a trip to the art museum. They do art and PE every day. Science, maths and English barely get a look in. They come up with beautiful art projects but academically, they are slipping so much I've had to offer them workbooks etc. at home.
Older girl was bored. Younger one was frustrated and her confidence suffered. They started pushing me to put her down a year because they couldn't be bothered helping her. (We helped her at home and now she's caught up and reading better than any of her class)
Oh, and fundraising. Loads of fundraising. They put up a jigsaw picture of each class on each classroom. When parents donated to the school's fund, the child's picture appeared in the jigsaw. Non-donaters were empty spaces for all to see. The PTA is like an in-crowd social club focussed around money - they auction off parking spaces at the school!
Unbelievable. The whole thing. It's also utter chaos, shoutiness and children barging into each other.
They're going to another Montessori school in September and I can't wait.
My advice is to find a school that will let your kids do at least a trial day there. I went through the options for new schools with mine and then they went for trial days at two of them. The one they're going to, they seemed to love and I'm happy that it's strong academically and will give them scope to learn and explore what they are interested in.
In the past, I let my older daughter do a trial day at a 'posh' girl's school and it was great for her to see what life was like there. She decided it wasn't for her and was happier at Montessori, but I'm glad we gave it a chance to see what it was like.
Also, it's obvious but when /you/ visit, pay close attention to everything - the wall displays, the other kids, the parents, the teachers, the head. If something doesn't seem right, have a think about it and figure out just how important that might be down the line (argy-bargy in lunch queues or whatever). Is it going to annoy you on a daily basis or is it trivial? Sometimes trivial things can end up being a big deal when your child faces them every day. And you can extrapolate a lot of information from one dirty toilet or one wall hanging with a strange message.