There is a GUI, but it defeats the purpose of the command line version, I think. Some people, however, have reported good results with Sib mplayer.

Never did what I need, but your experiences may be different. That being said: The command line version offers so much more than the GUI can pack in such a tiny space that a CL player seems worth the effort of entering commands.

Give it a shot, and try the GUI. Then try and play a video which has subs that are slightly out of sync. When I try adjusting the sync settings with both Gnome-Mplayer (a joke) and VLC on my linux laptop. With VLC it kind of works, but only for a short period of time. Usually there is also a cap to the amount of adjusting one can apply. So not the case with mplayer on the command line. It allows for extreme adjusting if needed while giving all the regular goodies out of the box.