I've only played on private servers, mostly because I read a lot of forums that all agreed on the "NEVER PLAY OFFICIAL SERVERS" thing.
Anyway, the game has its charm, but you're either going to grind an insane amount... or join a high rate where you breeze through everything in a re-tardedly fast fashion.
I haven't played the new classes, and the general consensus on every RO forum is that they ruin the game quite badly as they rape 95% of the content for free. So, if you want to check out the new classes, go ahead, but I've heard that they cause way more trouble than they're worth. Especially if you're into PvP(WoE yay).