Cambodian roads are not up to the mark, but you will soon get used to them. Buses are the most preferred form of transport here, as they cost less. In Phnom Penh, tuk-tuks are available for quick transport.
Cambodia Angkor Air serves the cities of Phnom Penh, Siem Reap and Sihanoukville.
Cambodia's railway lines connect Phnom Penh, Poipet and Battambang. Battambang's bamboo railway (nori in Khmer) is an interesting tourist experience.
It is easy to get around Cambodia by road. Privately run buses are run by lots of companies - Phnom Penh Sorya is the most popular one. Minibuses are also available and they reach destinations that regular buses do not. Share taxis are also common but are more expensive than buses. Other options would be to self-drive or to rent a car from one of the rental companies.
Boats do run in Cambodia, going from Siem Reap and Battambang and Phnom Penh and Siem Reap. Boats also depart from Siahnoukville to Koh Rong.