I got this on release, it definitely had all the work put into the first 20 levels, the closed and open beta limited you to 20 which kind of made sense when a few days after release the forums began to flood with "so... where the rest of the game?" threads. I think it was around lvl40 or so that the quest flat dried up and you had to just grind your way to the top from then on, there were a couple of instances in the game whilst levelling, they didn't work very well and only one them actually dropped any loot from the bosses. A shambles of a release state if there ever was one. Still, it looked great, it played great, the combat was awesome etc. After my free month I was done.
Queue the best part of a year later (a few weeks ago infact

) being bored to tears of WotLK I decided hey why not and put a month on this... and well, I won't be going back to WoW -- this is now simply awesome, has a very good level of polish, there are now quests left right and centre to the end (although i've read you can hit lulls in these and might have to grind a level or two to hit the next hub - but I guess thats only if you're skipping stuff and being boosted a lot) -- instances!, a hell of a lot of fun now, loot everywhere... ganking! was always there but now the game has matured a lot it is extremely brutal and unforgiving on the way up which only adds to the fun. still trundling to 80, so haven't experienced the end game, but theres a couple of tiers of raiding + the sieges now actually work, so can't be that bad (+ remember this is still a very young mmo in comparison to others)
Can't recommend this enough now tbh.
PvP is just a FFA, the only people you can't kill are either the ones you're guiled or grouped with.
Your guild builds a town, but they can't be conquered, but when you get a tier3 city (takes a while from scratch) you can conquer one of the 8 keeps in the 3 border zones for your guild (obviously there are more than 8 guilds trying to get hold of one), so they lay siege to each others keeps (calendar based so no 4am ninjas).
You don't loot people you kill, but there is a murder system (based on people killing low levels), killing murderers gives you a reward -- if you are a murderer you an no longer enter the regular hubs / cities because guards will kos you, so you will have to hang around the criminal camps in the zones and either continue your evil ways or try and work off the murder points.