Hong Kong has many advantages, such as a high level of education, strong sense of boundaries, civilized driving, and a strong awareness of queuing, etc.

But the place is too small, which leads to many situations that mainland friends might find uncomfortable:
Eating: Many restaurants have small spaces, making it hard to turn around; dining is time-limited; ordering can be unfriendly.
Playing: You can't even find a single chair in shopping malls — conversely, Hong Kong people are very healthy, either standing or moving around.
Expensive: No need to say more...
Hong Kong is suitable for big shots, Shenzhen is suitable for retirement. 😄