Well the game is very grindy, the quest give you nearly none xp, but you still need to do them because you get some free stuff for housing/trading and skill points.
You got action style combat with the melee classes, with the ranger for example you got an auto aim, so it's not entirely free.
PvE is not much there except giant field bosses that you won't be ablt to see most of the time because you won't see anything of all the effects of hundreds of other players killing it.
PvE is more about housing and building your crafting/trading network. For that it needs many hours of grinding to get somewhat automated so you can earn of it and have less need to grind.
Yeah PvP is great with capturing castles and such, but the class balancing is so broken... They are trying to fix it with awakening all classes, they get like that new abilities and new weapons. But the uppdate isn't even fully out in Korea and could take long time to get here.
To the classes:
Warrior: He got some nice bulk and cc, he's ok, neither bad or op.
Ranger: At the beginning great, but get fast repetetive with charging shots, jumping shots side ways, back etc. She' a bit of glass canon and has some melee abilities and with awakening she's fully melee, don't ask me why o.O
Sorceress: She's the favorite class of most players, with her you have the best chance to see what is possible with BDO's combat style. She's a melee mage, with many teleports/dodges and some range abilties.
Beserker: He got many ccs and melee aoe, he's great in massive group fights, but alone too weak.
Valkyrie: Similar to warrior, but she gets buffs and heals and together with the sorceress she's a tad op.
Wizard/witch: Great for fights against groups of enemies, he/she got the strongest aoe skills of the game, alone he/she's a glass canon.