IOS and Android do not support using exchange server they only support limited connectivity,
IOS does allow folder hierarchy to be viewed but not by default and it doesn't allow storage of emails in those so off-line use is impossible.
Android only supports a flatview of emails and folders, no hierarchy, and again will not cache sub folder data for off-line use, for both the default exchange client and third party apps. (I have read somewhere that ICS might have fixed this but don't know if it is true). No synching of notes either.