In most commercial Unix systems, the home directory of the root, or superuser, account is the / directory -- the root of the filesystem tree. In most free Unix systems such as *BSD and GNU/Linux, however, the root user's homedir is /root. This can lead to a certain degree of confusion in an installation where some systems are running (for instance) Solaris and others Linux or BSD.

Though my opinion is certainly biased by my preference for Linux, I suggest that giving the superuser a distinct home directory is a good idea. The superuser, like any other account, accumulates dot files and other state. Placing this in a distinct directory makes it easier to back up, or to replicate from one system to another. More generally, files which belong to the system can be clearly separated from those which belong to the administrator.