I'm from WoW, too.
Guild Wars PvP is focused on Arenas and Guild vs Guild battles. Arenas are for teams to challenge others, and test their skills in a group. The Guild vs Guild battles are great though. Guilds with Guild Halls can duke it out, and try to kill each other's Guild Lord in order to win. Everything has a point. For guilds, it's bragging rights, and for random teams, it's the chance to keep going as that team. Temas from different countries can also fight each other, and try to take the global favor of the gods for their region (America, Europe and Korea), but I'm not sure if this has any effect on the gameplay.
Everything is instanced except towns. Towns are major social points, and are divinded up into "districts." The districts are seperate copies of each town, and are used to spread out the population, so we don't get problems like Lagforge.
When you leave a town, you will get your own personal copy of the game. You will be alone, which elimates ganking and all that garbage. If you wish to play with a team, just group in a city, and when you leave, you'll have a copy of the game with the people you grouped with.
The storyline is amazing. There are seperate quests from the main storyline, in which you can just help the populace. Some are Fed-Ex quests, some are exploration quests, and most of the quests give item rewards. Some quests even give you new spells, which saves you the cost of purchasing them yourself. The main storyline is a blast. It is essentially made up of cooperative missions that you and friends can play, or you can just grab some NPC minions and go at it alone. The best part is that (with the exception of one coop mission, the Academy) you can return to the other parts of the world and continue to quest there if you wish. The coop quests also help to move the pace of the game, as a coop-quest will lead you to the next city.
Grinding is pretty much non-existant here. Other than in the first segment, when you might want to grind to get some items for the trading collectors so you can get your second set of armor, leveling can come solely off of quests. There is absolutely no reason to not have a quest in this game. If you can't find a quest, its time to do the next coop mission, which will take you to a new area of the game for more quests!
I hope this helps you make your own decision. I admit, I am biased, but the game is vastly superior to WoW. The patching system is by far superior. When you enter a new instanced sectio, the server checks for new files, and downloads in about 15 secs right there. They are then installed, and you can go about playing without having to restart the game! The only times you must restart is when Arenanet releases a new build of the game.
