Transportation in Hong Kong is incredible. Compared to Europe it's cheaper, cleaner and (almost) always on time. Don't forget to get an Octopus card first (http://www.octopuscards.com/consumer/products/apply/en/index.jsp)!
MTR
Very good and regular service
link: http://www.mtr.com.hk/eng/homepage/cust_index.html
Buses
Doubledecker buses can be found all over HK
link: https://www.nwstbus.com.hk/home/default.aspx?intLangID=1
Minibuses
These are the little green once. They have only 16 seats but are a lot faster than their bigger brothers. But you need to tell the driver where to get off.
link: http://www.hong-kong-travel.org/Buses.asp
Ferries
Hong Kong is an island, so sometimes you need to take a ferry to get where you want to. The service is good, fast and on time.
link: http://www.nwff.com.hk/english/schedule/search_route.asp
Transportation