a lot of it was simply because i didn’t enjoy the game, so you might find it more worthwhile, BUT it eats up i think…11 gb on your harddrive when all is said and done, and for me it was far too much for one game (i have the 20gb HDD). also, FFXI ‘bypasses’ the xbl dashboard, so there are some features you won’t be able to access when playing FFXI.
however, the 360/ps2/pc servers are all integrated, so if the above limitations aren’t a problem for you, then there really isn’t that much difference between the 360 and pc versions, at least as far as i know. if there are specific issues in-game that only 360 people have to deal with, i wouldn’t know about them. ^^;