The game has some flaw like the inability to dodge while some monster are meant to be dodged. overall, this game would have a solid 7... Until you see how much Kog, the game's publisher, is trying to get into your wallet.
-You have something called stamina. Every time you kill an enemy or complete a dungeon, the bar deplete. You can refill the bar by buying a potion in the Item Mall (cash shop). They can also be acquired through event or randomly by spending 3, hard to get, coin at a specific NPC.
-It take between 2 and 4 hour to empty the stamina bar.
-PvE can be done with spending a dime but you'll have to grind and PvP is far worst. You can perform well freely but you'll go at such a slow rate to get the gear needed compared to anyone how payed... So yeah, it's a P2W. Many will claim it is not but the same recurring excuse keep coming back: It take time... a LOT of time. And you'll have some trouble getting by while those who spend a lot never have a problem with ED (in-game currency).
-Beside that, you have to pay for character customization. Costume have stats and can be upgraded. It is a MUST for PvP and you can only get them in the Item Mall. All the best accessories are, mostly, obtainable from the Item Mall.
-You have some free costume but those are temporary AND can only be acquired once. So even if you were willing to buy them, you can't.
-Inability to hide they awful customization you get for free (You get an eye patch, cat ears, mustache, backpack and armpack early... try to have a cute of fearsome looking character with that...)
-You can have 8 slot for your skill but only 4 are free, you have to buy the other and you unlock some other slot for special skill you get later on but... only for a limited time, you have to pay afterward to have them permanent.
-You can't share stuff between your characters without paying. it is a must since...
-2 of the 3 professions for crafting require material can only be acquired from other professions. So either you buy from other players for an incredible amount of ED or you buy the share bank. And these crafting are useful for both PvE and PvP.
-It is a fast pace game, you don't want to go back and pick all the ED on the floor. Good thing they give you a pet with a temporary ability to pick up the ED for you. And the pet can only pet fed with food acquired from the Item Mall. Basically, pay up or pick up.
-All of the above wouldn't be so bad if the item in the mall weren't expensive... but it is. Too give you a perspective. The skill medal that allow you to unlock the 4 skill slot cost around 10$ and it is available for only 1 of the 12 character you can have. Accessories will cost you between 3 and 6$ a piece, and you have 10 slot for accessories. Costume? It range between 3 and 7$ per piece and you can have 9 piece that, remember, they aren't just aesthetic, they give minor stats boost. Quick math you'll spend, at least, 67$ for your character (going with the minimum price possible). I haven't included a descent pet, the permanent fetch skill and the other skill slot that can be unlocked. AND ALL OF THIS FOR 1 CHARACTER!! One Character that you can build to max level within a few week... That is insane.
But still... you can get everything for free by grinding hours and hours, only stopping when your stamina bar is empty. Paying a astronomical amount of ED to acquire every thing you can get since everyone agree on one thing, the economy in the game is broken (Long lasting game where in-game currency isn't often enough spent into NPC make an inflation. New players always have a hard time getting by because of this.).
In the end, try it, it's enjoyable. But Kog's greediness will, most likely, turn you off.