Is Miss Jean Brodie a great teacher or a monster? Or both?

Everyone knows the movie "The Prime of Miss Jean Brodie" (it was one of those PBS-style movies of the 60s? 70s? that everyone saw in the days before there was nonstop BBC on cable; it introduced Maggie Smith and red hair to America), but fewer have read Muriel Spark's book, and that's too bad. I'd never read it, started it last night prompted by a few reviews I read of a new bio of Spark - most of her work sounds unapproachable but Miss Brodie pretty much acknowledged as her best. It's short, not much more than a novella, and from the start anyway very well narrated and quite provocative. I guess the question it poses right away is: Is Jean Brodie a great teacher or a monster? Or a little of both? Her "girls" are very devoted to her, but I'm not sure that's necessarily good. First, they become a separate a isolated clique in the school, and I don't think a teacher who encourages her "girls" to believe they're better than all others is a good teacher. Moreover, what makes them better? Apparently, simply contact with Brodie. It's all about her - that's obvious - and what the girls like about her is not what they're learning but what they're learning about Miss Brodie - her love life, her travels, etc. This is not good teaching. And yet - in a way she does inspire them and make them want to be and do their best. The school doesn't like her and is trying to push her out, into one of the "progressive" schools (it's the 1930s, Edinborough) - that's the spark so to speak that ignites the plot - but it's not clear why they don't simply fire her. I guess that wasn't done. They're probably not wrong to want her out, but she'll put up a row, as they say.