Hong Kong is still a vibrant and exciting city. It will probably, in time, lose its distinct character and become more like any other large city in China. Hong Kong has spectacular architecture, a wonderful natural setting, and is a pulsating 24/7 metropolis. The food and nightlife are amazing. The transport systems work well. Imagine New York City, but with dragons!
Sadly, however, Hong Kong has lost its freedom, and is now under the heel of a ruthless authoritarian government. The criminal justice system is no longer independent. The business courts are still independent, but it is not clear for how long this will remain the case. If you are going to Hong Kong, go soon, because the old Hong Kong is vanishing.
Cantonese culture is very interesting, but please note that some Cantonese people can be a bit racist towards people of African/Caribbean ethnicity, and to a lesser extent towards people of South Asian ethnicity. You might find that you are stared at if wandering around a street market, and you might sometimes be treated rudely by Cantonese people who are not well educated, although you would not be at risk of violence. This is not a reason not to go to Hong Kong, but just be aware that HK is not always as tolerant a place as, say, London is. Educated Hong Kong people are no more likely to be racist than educated people in most places.
Expect to live in a tiny apartment and pay a high rent for it. That's the Hong Kong way. The streets are bustle, bustle , bustle. Hong Kong is one of the greatest cities on the planet.