Well I don't really understand the storey atm. You start off at a place called Tortage (basiclly beginner land) and for the first 20 levels the main storey quests are offline, once that is completed you can leave Tortage (after finishing the main quests) then the world really opens up, seriously it's bloody huge! Some quests I have to go through at least 2 maps (one map from corner to corner to run takes about 4 mins if your not attacked or ganked) then you have to run all the way back. but it is really worth it.
Once you hit 40 you can use mounts, build guild cities and have sieges on the guild city by other guilds etc. which is great with pvp like 100 people attacking each other, huge mounts that you can attack off.
The combat system is great. 1,2,3 and on some classes q,e are attack buttons. 1 attack left, 2 attack forward, 3 attack right so on.. To do combos I would press the number to start the combo then press any of the following attack keys. So if I wanted to do a cunning strike (one of the combos) I would press 7 (the number I have binded to it) then 1 then he would do the attack. It's better than spamming 2 (like in WoW

)
Oh and the defense system is pretty good. If you keep attacking to the left the AI will change his defense so that he will take less damage while you're attacking to the left.
Longest post i've ever written on OC3D xD.