I agree that sync is hard and I wouldn't even blame iCloud since it's rather complicated matter, but there are three things that made me do so:

1) They made it a de facto standard and showed developers how easy it is to use when seemingly, it's not

2) iCloud even messes up simple sync tasks, like: buy a new device 3 out of 5 apps won't start after a simple download from iCloud

3) The problems occur to so many customers and developers that Apple should communicate the problem with developers and adapt their approval system.