I'm in favour of a GUI. Command lines are nice and fast, but a GUI is self-documenting. It's pretty obvious what a checkbox labeled "allow spectating" will do, but to do it from the console do I need to type "/spectate on", "/allowspectate", "/enablespectate" or "/spectate 1". I tried more than just those the other day before giving up, looking through the readme, and finding that it was "/spectating on".