If you're looking for a game with enless amount of quests and sophisticated level-ups system, then this might not be for you. This game reply more on the interaction between player vs. player, rather than player vs NPC. Apart from teaming up with your friends and kill monsters, and enjoying the amazing graphic at the same-time. You can like siege castles with your clan, or protect the castles, which are won over and controled be other players rather than NPC. The clanleader who successfully defeated other players and controled a castle can set taxes etc which control the economies of the game world.
However, if you can be easily bored, the start might be a bit off-putting, because it is not a forgiving game, you need to spend many many hours to level-up, cash to buy equipment is hard to earn and good equipment is crucial in this game. The punishment for dying is harsh. Also especially when most of the interesting things that you can do like castle-siege is aimed for higher level characters only, and good-looking weapons/costumes which make you like your character a lot more, are also available to high-level characters only.
PS This game is not quite suitable for casual player who have only very limited amount of time to play, because it does take a lot of time and patience to level-ups, especially when you don't have any money or friends to help you.