Quick and easy to set up.
Network protocol is stateful and noticeably faster than WebDAV.
No need to create system accounts on server.
Password is not passed over the network.
By default, only one authentication method is available, the network protocol is not encrypted, and the server stores cleartext passwords. (All these things can be changed by configuring SASL, but it's a bit more work to do.)
No logging of any kind, not even errors.
No built-in web browsing. (You'd have to install a separate web server and some CGI software to add this.)