XI's UI was wonderful for a keyboard only or game pad.
But it was the worst thing on the planet for a mouse... it simply sucked for it... completely menu driven PS2 UI with almost no Mouse support at all.
Honestly what I loved most about FFXI was the lack of UI clutter on the screen and the usability and functionality of the chatbox. Everything could be controlled with a few key clicks. and the screen was for the most part left clear.