Level Balance in PVP issues as well as no HP/MP full recovery after death in PVP.
The level up system is just right. It is not easy and between normal-hard. My experiences with leveling is quite challenging players when it comes to logic about manually applying Status Points on your character build status. Unlike most mmo-rpg provides players auto set of status builds, but it does differently in Ragnarok Online and it tests your I.Q and wits wether you are both intelligent and a successful player.
Monsters:
The monsters there are interestingly attractive to Pokemon gamers, because you will notice some super effective moves and not effective moves as well.
Skills:
Skills, there is no doubt the most interesting there than any other game. It also test your decision and wits as well as how you manually decide to apply your Status Points.
PVP:
The review Deck says it all. The PvP doesn't provide auto Full HP/MP recovery after Death in PVP and it requires to pay 5000z for full recovery within Inn. The other issue is about the balance. The only pvp channel there is Free for all. Imagine a low level is excited but eventually die like a piece of booger and sink. It discourage them to level up instead keeping their self-esteem higher if there are level limits on PVP.
I just explained to you everything why Ragnarok Online is extremely not popular in USA. USA stands for JUSTICE, so you know! American players hates unjust PVP. PVP is like mmorpg icon to keep it alive that's why Ragnarok is dead forever! Asian games are generally corrupt!