Like KO, getting max level is pretty boring, questing and what not. But also like KO, grinding through the instances is good combo practise for endgame + chance to get some pvp buddies. Theres a pvp ranking grade system, elaborate combos (more-so than KO), a standard MMORPG clan system, several thousand users online, mostly english people (and you can choose US or Euro server). Game is still pretty young, not many pros to take me on yet.

C9 - Korean Best Assassin Leaving - YouTube

Heres a video of one of the most pro comboers i've come across (KR kid, obviously)

CBF putting the effort into making a proper thread to do the game justice, but eh check it out if you wanna.