There are two kinds of people in the world: those who have no problems with iCloud sync, and people who use iCloud sync. Well, OK, maybe that's an exaggeration, but I have had plenty of problems with iCloud sync well back into the MobileMe days.
Most of the problems relate to syncing contact data. For some reason, iCloud periodically stops working in some non-obvious way. The way I usually discover this is when I realize that some device does not have some piece of information which was either added or changed on
