Agree with most of that, not least the really friendly Khmer people, but an alternative to tuktuks is Phnom Penh's "CityBus" service. All buses have aircon and a flat fare of Riel 1,500 (around US$0.35) irrespective of distance with a CityBus app so you can see all the routes, all the stops, and where the buses are. Mostly daylight hours only though. The service officially runs until 20:30, but don't expect to find a bus after 19:00, nevertheless a good way to avoid the airport taxi sharks as there is a #3 bus which stops just oustide the passenger terminal (exit the car park, turn left and walk 150m) and which will take you downtown for US$0.35!