Well, now that OS X Mavericks has a .1 update, with the concentration being on Apple Mail and Graphics, it would be safe to say that OS X Mavericks, like iOS 7, is possibly the worst release of OS X ever. The completely untested releases, not to mention the non-existent UX.
Mavericks, true to it’s name, is one. Almost nothing works as expected. Although Apple acknowledged issues in Apple Mail, it was limited to Gmail related accounts and mentions nothing else. It still has a clutter of draft/versions and sync issues. The rendering of standard HTML email still does not work.
The Contacts still retain the bloat and duplication issues of earlier. All iCloud applications require manual run to sync them across devices. The iCloud Keychain does not work for Exchange accounts…try changing an Exchange account password after the policy expires it. The more iDevices you have on the iCloud Keychain, the worse it becomes.
Nitin Chandra's Blog 