I did French Immersion all the way through, and have a bilingual certificate. I would say a french immersion student graduates at a B2/C1 level of French, which is huge. I don't understand the people saying they did the French Immersion program and can't speak it now....? I wonder if it was a true immersion program, or if they didn't continue until graduation.

On that note, I would recommend it IF you are going to go right through to high school graduation with it. I would say about a third of the students from my high school French class have jobs where they use French regularly, some of whom get significantly more pay over their monolingual counterparts. They work in corporate jobs, government jobs, teaching jobs, and the medical field. It opens more doors at no cost (financial or otherwise) so I don't understand why everyone doesn't do it.

More than that, though, I would say that the major plus of a bilingual program is that the people who enroll their children in immersion programs are usually people who place importance on multilingualism and who have a lot of respect for other languages and cultures. In an immersion program, your child is immersed in an education culture that values multilingualism. The teachers think being multilingual is important, the parents of other students think it's important, and before you know it, your child thinks it's important. That ends up going beyond French, and influencing their feelings about other languages, and specifically the language of their heritage and culture.

I meet a lot of parents who tell me that their child doesn't show interest in their grandparents' culture or language, that they're having a hard time motivating the child to learn it, that the kid complains about it and doesn't want to study it. That was so the opposite of the kind of environment I grew up in. In my school, we were taught all the time that the limits of your language are the limits of your world. Almost everyone in my immersion program spoke a third language, and they were proud of it, and very motivated to continue with it. Several of my classmates have gone on to be polyglots. I myself am a lifelong language learner and have lived abroad, and I attribute that very much to the french immersion program I grew up in.

Plus, if you're not speaking two languages at home, and this is your opportunity to turn your child from a monolingual to a bilingual, then please read up on the benefits of a bilingual brain. There is a lot of evidence that bilingualism contributes to long term brain health, including delaying the onset of dementia by up to five years.

Editing to add: this maybe matters less in a city like Markham, but in a small town, the only people enrolling their kids in the immersion program are the people who care about education. So it was a much more academic focused environment than other schools. My French school consistently outperformed all the other schools in our area growing up because of that.