Okay, I've played FFXI for just over 2 years now and done a lot on it, as with most MMO's FFXI is very slow to progress through, however it gives a sense of accomplishment and satisfaction much higher than any other game I've tried.
On a visuals note, I'd say this is one of the best looking MMO's you'll find, especially for detail and variety of area's and armours, it's all very detailed albeit kinda low-res since its on PS2 as well as the PC/360. Even so it has a far better look than something like WoW. Sound is also nice, especially BGM music.
Gameplay all depends on your level and job choice, from 1-74 you'll be grinding to hell levelling up, and it isn't a quick process the first time through. There are things to do still, missions and quests for example but the game only really opens up when you hit lv75 and get to the "endgame". There's absolutely tons of things to do at endgame, I wont get into the specifics because it wont make much sense if you haven't already got knowledge of the game.
Now, if you're new to FFXI and don't know people already playing it who can help you out at the low levels you will struggle, FFXI does not hold your hand and there is very little in the way of a tutorial to show you how to play, if you're coming in to this yourself it will be hard. This is a 5 year old game, most of the playerbase have lv75 on at least one job.
Last thing, one of the best things in FFXI is that you can have a single character and you can level all 20 jobs on it to maximum level and change between them when you like.
In short: Recommended if you already know people who play, or are starting with friends. Not recommended if you're starting on your own and dont know anybody.
Hope someone find this useful.