[Beta register] Echo of Soul was really popular when it first launched in South Korea, and the momentum there has carried on till now (even for the China server). Aeria Games just announced that it will be publishing the English version, which will arrive this coming spring.
I did not cover the Korean version of the game, has it does not have really any major feature (though earned tons of cash). There are 5 standard classes (Warrior, Guardian, Rogue, Sorceress, Archer) with the new Warlock class reaching later. There are also some professions such as chef and alchemist.
The major features in Echo of Soul must be the various PvE and PvP modes. For PvE, there is a 20-man raid where players will face a giant boss at the end. Strategy will be important, and it is up to players to coordinate with one another. Currently, there are several other pretty standard dungeons.
For PvP, there is the guild vs guild battle, where a giant PvE boss will spawn after one is defeated. Guilds can declare open world PK against other guilds as well! There is a “capture the flag” mode, where low level players will be buffed up to party with the high level players. Finally, several other standard battles such as 5 vs 5, 15 vs 15 are available. Also, experience points can be earned via PvP.