Be prepared for non standard ATC terminology such as "expect 2 turn in the hold" or "fly heading 180 for a while". The busier airports are controlled chaos but things seem to work okay if you go with the flow. Unlike Australia, ATC can't be bothered reporting pilot screw ups and a simple "sorry" will usually do for the minor infractions, major stuff might require some folding to change hands. Indonesians prefer to avoid conflict situations but if you cause someone to lose "face" it can get ugly very quickly.
The biggest annoyance is the idiots making animal sounds on 121.5, usually cat meows but other species can sometimes be heard.