In the dictionary for "MMORPG" you'll find this entry: "see also: FFXI." This game defines the genre
So many MMOs these days completely lose the point of what an MMO should be. They seem to focus on single-player game play set in an environment where other players occupy space. What's the point of that? MMO should be about community. It should be about banding together to defeat foes, working as a team. That's where FFXI shines. You won't be soloing much in this game, unless you're either masochistic, or choose to play as a beastmaster (which is borderline masochistic.) The game virtually forces people to work together as a cohesive unit in almost every aspect. From leveling up, to fighting some of the toughest monsters in the game, quests, missions, etc. They almost invariably require a balanced party.
Some words of warning though. This game is not for people who don't like to work with other people. It is also not for people who lack patience. Nor is it a game that you can log into for half an hour and achieve much. This game requires time to do much of anything. And lots of it. Whether it's trying to get a group together to grind out some XP or knock out a quest or mission, you'll find yourself taking a while to prepare, travel, and eventually get to the goal and (hopefully) win.
Things build very slowly at the start for someone new to this game. Like many other MMOs, your character is nothing but a newbie at the start. He'll have very little skill in anything, bad gear, diddly-squat for money, and no clue what to do. You're basically plopped down in your home nation, and what you do from that point is completely up to you. The game tries to nudge you in the direction of starting the chain of missions for your home nation, and that will help to give some direction. Your best bet is to befriend a veteran player who can mentor you though. Listen to what they say, because they'll more than likely give you some sound advice.
There are so many aspect of the game that are excellently done that it's hard to pick where to start. I guess having the capability to keep your character and choose a new job at any time is one of the attractive qualities of the game. As you progress through the game there are many obstacles to overcome. Things like getting an airship pass, unlocking access to certain areas, questing for things like key items, maps, etc. All of that is linked to your character. It's wonderful to be able to go into your house and select a new job and not have to worry about grinding those same quests again. Repetition of quests is not my idea of fun.
Another great concept is the ability to tack a subjob onto your main job. This is what really separates FFXI from a lot of other MMOs. A Samurai with a White Mage subjob will be significantly different from a Samurai with a Warrior subjob (and a SAM/WHM will also be laughed at, but that's a subject that's best for forum fodder.) Besides subjobs, the obvious way to customize your character is via gear. There's tons of gear. Some of the more mundane items are easy to get, and typically the best gear is incredibly difficult to obtain. Beyond subjobs and gear, there's merits to further customize your character. Merits are points your character earns once he has leveled to the cap (currently and probably forever at 75.) Merits allow a character to enhance statistics or unlock job specific abilities. There are only so many merit points that can be spent in each area, which was very wise on Square-Enix's part. This way not all players can be the best at every job they level. They have to choose wisely which stats to enhance.
There are some drawbacks to the game. Square-Enix has been notoriously bad with progression. Where other MMOs have released expansions that add newer and more powerful items, SE still to this day has not added better or even comparable gear to the gear release 5 years ago. To compound this problem, the monsters that drop this gear are world spawns on 24 hour timers, and the items are a low percentage drop rate on top of it all. This means that every end game player that desires these items are constantly camping the monsters that drop them. And, if things weren't bad enough, many of the people who camp them have resorted to botting the spawns, meaning that the chances for players who do not cheat to get claim on them is very, very low.
Other bad things about the game is the perpetual excuse given by Square-Enix whenever a technical problem surfaces. The dreaded "Playstation 2 limitations." They love to toss that out there as a reason to not do something, like give players additional inventory space, or repeated use of the same armor/weapon models, etc. Crafting is also pretty bad. Many items that can be crafted just aren't worth anything, and will often cost more money to make than they will sell for. Almost every piece of crafted gear has a quested item or item that drops from a monster that is better than the crafted piece. The better crafted pieces are typically very very expensive.
This brings us to another problem in the game: earning in-game money. This is probably one of the most difficult games to earn money in. There's negligible loot dropped from most normal monsters. Typically the rare monsters (they're called Notorious Monsters, or NMs for short) are the only ones that will drop items worth anything, and of course those monsters are heavily camped. Earning money is one of the most challenging aspects of the game. I'm not sure if that's a good thing or not.
I really have only barely scratched the surface of the game in this review. I've not even gone into any of the hundreds of activities this game makes available to players... chocobo raising, brenner, farming, assault, campaign, salvage, einherjar, the list just goes on and on.
The bottom line is it's a game that you should never, ever find yourself bored in. There's always something to do. It may not be exactly what you had in mind. For instance you might want to get in an experience points party with your Dragoon, but a party for a dragoon is hard to come by, so you will seek for hours. In the meantime however, you can go off while seeking and craft, or mine, or take part in campaign, solo a little bit to gain skill with a weapon your character isn't very proficient with, etc. If you're able to get past the steep learning curve and make friends with a veteran who can help guide you, and your a person that has lots of patience, this is a game you will play for years and come back to again and again.