I'll take a stab at replying in comprehensible language.
(though I'm sure someone will find something to dislike!) (I found my way here through Google looking for Atlantica fansites, though I've read the Escapist more than a few times)
I'll admit I was incredibly skeptical regarding Atlantica, but there was enough buzz at some of the MMO gaming sites that I thought I might give it a try.
The two most recent games I have played for more than 40 hours apiece have been Fallout 3 and Warhammer Online, and Bioshock/COD4 prior to that. Those are mostly mainstream, popular and well-built games, and most of them topped out on my attention-o-meter after 40 hours or so (with the exception of Warhammer, which I played 100+ hours).
So far I am around 120 hours into Atlantica, and still jonesing every day at work until I can go home and play. For those willing to put some effort into the game, the rewards are great. There are definitely some quirks to the game, and not everything is perfect, but the game is so...full...that it makes me overlook many of the flaws.
Tactical Combat - To the commenter who said turn-based combat should be single-player only, all I can ask is why? Turn-based combat in many ways lends itself to more strategy than your average twitch titles, and Atlantica bears this out. There are many ways to be successful in combat, from defensive grinds to area-of-effect/disabling builds to brute force lightning builds. Some may be more or less effective against certain monsters/player types, but that also requires adaptation and the ability to learn.
Crafting - Every item in the game can be crafted, and there are over 30 crafting skills. There are 3 sets of weapons and armor that are at the top of their tiers and can only be created through crafting. I'm only a low-level crafter but it looks like there are several hundred crafting components. Mid-level crafters can also gain crafting exp by training those of lower level, so there is no relying on NPC's to level up your skills.
Economy - Everything can be bought/sold on the open market, with the exception of a very few licenses (items that make the game not easier tactically, but administratively, such as the ability to teleport to a location you have been to and additional inventory slots, etc). The crafting/economy sections of the game are a little bulky (and dear lord I wish they would alphabatize the tables), but are as fleshed out as those in Eve Online.
Guilds - Guilds can take over towns through an auction process, which allows them benefits such as tax revenue and additional crafting ability. Guilds can combine into nations which in turn can war on other nations.
Help System/Teamwork Building - There are a number of devices embedded in the game that help ease players over the sometimes steep learning curves of the game. A mentor system allows an older player to partner with a newer one, providing benefits to both. The mentor receives bonus points which can be used to purchase special items and a sizable cash payment once the mentoree reaches a certain level; the mentoree receives basically an unlimited helpdesk able to answer the majority of questions that may arise, as well as occasionally providing monetary or item assitance.
Additionally, there is a 'help' system that sends a person's question to everyone in the general area that might be able to help; if a respondant is actually helpful and answers the question, they receive a small reward.
Knowledge Tome - Not quite as extensive as Warhammer's Tome of Knowledge, the Knowledge Tome (I don't know if it even has an official name) contains information on every creature you meet, all the quest givers, crafting teachers, NPC's, abilities, and locations of the game. Monster knowledge is actually improved as you fight each creature, to where it will eventually keep a database for you of which monsters drop which types of loot, equipment and crafting items.
Consensual PVP - There is ranked league combat where you gain some exp/rewards whether you win or lose. Additionally, there are titles associated with reaching certain tiers. There are also weekly championships with some pretty hefty prizes on the line.
It is true that along with some great systems, there is a good deal of wonkiness to be found as well. The plot is pretty linear and is obviously translated from the original Korean, but I actually find myself becoming attached to the storyline/world. For the commenter who said it looks like 'another generic pseudo-medieval fantasy MMO', you are both correct and incorrect. Some cliched themes such as family, loyalty, betrayal are here, but the monsters of the world, while including some generic staples, also includes some twisted and very cool creations. Unicorns with swords instead of horns, parrots with additional appendages, winged tigers, jaguars that summon little hordes of jaguars, human-inspired wasps, tuxedo-wearing butlers with swords for arms, among dozens of others. I actually almost quit the game when I first had to do battle with a pack of Deer, but after some fights with the various denizens of the world, the 'offness' of the creatures shines as a strength.
If you remember yourself being addicted to games like King's Bounty, Disciples, or Final Fantasy 7, then Atlantica will almost certainly appeal to you. I didn't expect to fall for it like I have, but if you want an MMO that really is different, it might be worth a shot. It is free after all, and even that is well done. While there is an item mall, none of the items provides significant tactical value, and are convenience-driven. I played the first 50 levels without paying a cent; I did end up buying some licenses recently, but more because I wanted to support a developer that actually created a unique, enjoyable product rather than any ingame need.
Oh, and if all that is not enough, the female toons are hawt!
