I'm actually really enjoying Wonder King. The graphics, music and monster designs are appealing to me. Also, the equipment designs are -very- good, in my opinion. You really don't even need to buy Cash Shop clothes in order to have a great look for yourself.
Leveling is very easy, so it's definitely a game even a casual gamer can enjoy. I myself don't spend that much time on it, but I easily made it to Lv.5x with just a bit of questing and easy grinding here and there.
I like that the bosses that drop great equipment, and give great exp are instanced so you don't have to pray to god that someone isn't killing all the bosses you have to kill on every channel. Get some friends, party up, fight the boss and gain lots of exp, great gear and money to -easily- fund yourself.
The hackers can be a pain sometimes in certain areas, but thankfully there aren't nearly as many as there were back in CB. (If there were I would have quit..)
Overall, it's a pretty great game worth checking out in my honest opinion.