Mandarin at the expense of English?
Not sure whether you are familiar with the ACER test, a test designed for international schools and conducted by Australian Council for Educational Research (Home | ACER). A number of international schools in HK take part in the test (including Chinese International School and Canadian International School). The results for the 2010/2011 round of tests were out about a month ago. In mathematics, ISF students' scores are statistically significantly above HK average. In reading and narrative writing (English), the ISF students are above average (but not statistically significant). In expository writing (English), ISF students are again statistically significantly above average. Chinese is not a test subject in ACER test. It it were, I'm quite certain that ISF students would far far exceed average in the Chinese department.
The immersion mode is working. The lower primary kids who are taught Chinese math do well in the ACER math test, which is conducted in English. Obviously the students are transferring the concepts and knowledge learned in one language for use in the other.
Some say ISF is not international enough. Not sure what it means. If you look at the kids in the primary section, about 1/3 of them are native English speakers from all over the world, 1/3 of them native Mandarin speakers from China/Taiwan/Singapore..., and 1/3 of them from local families. Is this not more international than a 100% English speaking school where some of the kids and their parents are simply ignorant and disrespectful of Chinese/Asian cultures? Show me another international school whose students can do like "River Cultures vs. Ocean Cultures", "Roman Latin vs Ancient Chinese" in both English and Chinese languages.