Roustem Karimov of AgileBits (makers of 1Password) has a good post on their experience with CloudKit:
CloudKit is very fast, efficient, and makes it easy to detect and troubleshoot errors. CloudKit is predictable. 1Password now knows if the item was successfully updated on the server and is available to other devices. If the operation fails, the app now gets a detailed error message explaining why it happened, be it a network error, a downed server, no space available, or the user was rate-limited.
We don’t have to guess when something goes wrong anymore, and we no longer have to tell our users to perform a set of magic steps hoping that some of them would trigger iCloud to work. CloudKit solved the problems we had with the old iCloud.
When it rolled out in 2011, many developers complained about iCloud related issues. So it's good to see this positive take on the new iCloudKit.
[via John Siracusa]