I want to ask is Queen Elizabeth School is a good school?

Queen Elizabeth School is definitely a good school.
Traditionally, it is a famous brand 1 school. In fact, it is the most famous public school in Kowloon side.
As stated by her headmistress:
"Nurtured by the liberal, harmonious and stimulating school atmosphere, our students are inspired to become passionate life learners and participants, making themselves builders of Hong Kong and citizens of the world."
According to the website you provided, the students of QES won many local and international awards, which indicated their students are all-rounded.

the potential of this school is okay, but the environment of that school is quite complimented, u must also think about this question!!