Hrm, hate to ressurrect an old thread but I had to comment. I don't know how I missed it the first time. :lol
Buggy's relatively outdated with FFXI trends but he's right, of the 4 original Final Fantasy games of the PS2 generation, FFXI is by far the best. Its gameplay, story (which don't really exist in MMOs except for FFXI), lore, and etc turned out far better than the other three games. Once you get into it, you realize just how much depth there is to the game. The job system, the overall flow of combat, the structure of spells and skills, the battles and their setups, and a bunch of other things fit so well together and makes the entire game incredibly satisfying.
Of course, the greatest problem is that it's an MMO. It suffers the same pitfalls that all other MMOs do. The community can be awful and that in turn makes grinding painful (although grinding in FFXI can be FAR faster than most MMOs) and the economy a possible hell hole. There are some updates and systems that could used a lot more thought put into it and the game's storyline battles are brutal making it for the really masochistic.
If you can get past it though, the game is just so incredible. I finally finished the Chains of Promathia expansion tonight with some friends and a few GAFfers. It's been our project for the last two months or so and it was a helluva ride with some of the toughest battles I've ever encountered from a MMO or otherwise. The sense of accomplishment and relief most of us got from doing these battles and defeating them is just incredible. Some of these battles were absolutely epic, something I haven't felt from a game in ages. There's just something about you and a group of friends taking down a god that gets your blood going.