To be precise: There is a regular root-user, but no password is set.
By default you get root-access in a terminal by for example running "sudo su -" and entering your user-password. "exit" leaves and brings you back to user-level. You can also just execute a single command as root by running "sudo <command-name>".
If you want to be able to directly log in as root you need to set a password for the root-user. Run "passwd" as root to do that. But this is not really necessary. I also modified the first line of /etc/passwd and replaced "/bin/sh" by "/bin/bash" in order to have bash as default shell.
Edit: Regarding the process of switching to root from within a terminal the difference is not really big. With a root-password set you can just write "su -" to become root instead of using "sudo su -". But if you for example connect to the Pandora from a remote shell (like ssh) then you can log in directly as root from another computer by running "ssh root@<pandora-ip>". Without a password you would first have to log in as user and then switch to root.