With huge respect to Ron - almost all settings are available through OBi Expert configuration menu; and if you are new to OBi, you are most likely not experience any difference.
So, if your device is on the LAN, then it probably doesn't matter; but if you are planning to administer it remotely - I found expert configuration menu to be a huge convenience!
Note, however, that the documentation is outdated, and barely mentions expert config. But if you follow the instructions for configuring the device, you will see pretty much the same options as well