The access to internet is quite good in Cambodia, particularly in the urban Cambodia such as Phnom Penh, Battambang, Siem Reap & & Though the internet speed is not as good as Bangkok or Ho Chin Minh, but it is faster than Myanmar and is quite cheap.
Internet in Cambodia is probably one of the fastest and most accessible across Southeast Asia. WiFi is available in the vast majority of coffee shops, restaurants, bars and hotels, and even on some modes of transport. Tourist SIM cards can be bought at the airports on arrival for a few dollars.