One of the deepest online multiplayer experiences you'll ever find, and I hope to help you decide if it is right for you
The Xbox 360 version of this game, with all expansions installed, will take up about 11 GB of your HDD. If you don't have a hard drive, you can't play. If you've got a 20 GB, you may have to make some room. Just make sure you've got the space.
Got the HDD? Good. Now, you're going to need a USB keyboard, preferably a wireless one. The chatpad is probably not the best option, because it is missing some important keys, not to mention you're going to be able to type much faster with a real keyboard. I highly recommend a Logitec wireless keyboard, as I have had bad experiences with off-brand wireless USB keyboards simply not working.
Now, the question is whether or not you want to buy the game! As of the time of this writing (3/30/09), You can buy the Vana'diel Collection 2008 (game + all 4 expansions) for about $20 at major retailers. That's a pretty low cost for a lot of content, and it comes with a 30 day free trial, too. After your trial ends, the cost is $12.95 per month for 1 character, and an additional $1.00 per month for each additional character. You really just need 1 character, since you can change jobs as many times as you want in game, but you can have up to 16 if you'd like.
Now that I've talked about cost, what about gameplay? One of my biggest problems with the game is that it can be very unfriendly to new players, because it doesn't bother explaining things very well. There are numerous guides online to help you get started, and Square Enix has made newbie videos on PlayOnline's website to help you get started. Some excellent resources include ffxiclopedia.com and ffxi.allakhazam.com just to name a few.
To get the most out of leveling your character, it's best if you can play in 2-3 hour blocks. If you don't have this kind of time, it's still possible to play, but you may find yourself struggling to get exp. If you're a new player, you will be happy to learn that Square Enix has made leveling much easier with the inclusion of the "Level Sync" system - the ability for higher level players to temporarily level down to match a player in the party and still earn exp - and the "Fields of Valor" system, which gives small monster-killing quests that reward you with a decent experience and gil bonus upon killing all the monsters. Think of it like monster bounty hunting! It makes the game much more enjoyable and may give you something to do while waiting to get a party started.
One of the greatest aspects of this game is its community. The people (for the most part; there are always exceptions) are friendly, fun, and very helpful. By being nice people, you make friends, get invited to parties, and get linkpearls. It's in everyone's best interest to help each other and work together; after all, it's a social game.
My biggest complaint about the game is that its interface is not very intuitive. It's extremely menu based. Creating macros helps ease this a bit (there are resources online on creating macros), but it's still annoying. Quests and missions are usually so vague that you could never figure it out on your own. Again, online resources are invaluable to aid you in this plight.
What? No actual review, you say? Alright, here goes: I give this game 9/10. It is a complex, rich adventure with a great storyline and a deep battle system. There is so much content that you could play for years and there would still be more for you to do. It has its nuances and problems, to be sure, but the overall experience of the game compensates for it. Go ahead, pick up a copy and try it out. Keep an open mind and a friendly manner, and I guarantee you that good things will come your way. Fun, friendship, and foes await you in Vana'diel, so hop on your chocobo and ride!