The public hospital system is excellent.
My wife gave birth in the Queen Mary, and our second child due in a couple of months will be born there too.
The Queen Mary hospital has the best of facilities, including the neo-natal ICU, and it is where neo-nates are rushed when it goes wrong in the private hospitals.
I have a few colleagues that had experiences ranging from unfortunate to tragic in private hospitals in Hong Kong.
The only downsideof the public hospitals is that Hong kong hospital food is nasty. Not because it is chinese food, but because it is hospital food.