As time goes on I see more parts of OS X breaking for the root user. This week I found out that the root user's keychain is buggy in Mavericks. Most passwords do not store/retrieve, and apps that expect the keychain to work will bug also. The only serious problem I've ran into in relation to this is that mail is no longer useable by root.
The skinny of it: when you set up an account, if you enter the password, it tries to store it in the keychain. Or if you don't enter it and it prompts for it, it tries to store it. THEN it gets it from the keychain to check mail. This process fails, silently, and it will either take your email offline or will prompt again. The end result is you cannot do password-authenticated sending, or any form of receiving.
I've reported this issue, but as with several others, I doubt they'll spend any serious time to fix it. They consider the root user to not be a "real user", only to be used for troubleshooting purposes. I know some of you here agree with that, but my service drives at work are all logging in as root because otherise I'd be spending a lot of time typing passwords.
(root also has problems toggling owners on external hard drives, diskwarrior won't run, and I'm having problems recalling the other issues offhand)
I work for the Department of Redundancy Department