Ben Bajarin writes about iCloud’s virtues as a sync tool:
The thing that is interesting about the cloud and synchronization, is that it is only truly valuable when you have multiple devices you want to keep in sync. When all one owns is a single device, there is no need to keep things in sync. All the content you own and produce resides on the device and the services that device connects with. As you start acquiring more personal computing devices you begin to spread time and data across them all. Keeping things in sync is an essential part of the multi-device experience.
Ben’s piece is a good complement to the one I wrote on iCloud document management.
I use iCloud sync for many things, and have found it to work very well. iCloud does have its share of issues, but I would say the sync aspect is one of its better features, in my experience at least. I’ve not had one problem syncing documents and the like across my devices.