This post started off as a reply to NokkonWud, but as I went into so much detail I thought it might as well come in handy to others considering getting the game.
Guild Wars is broken down into three core games:
* Prophecies: the original game which is the closest to a traditional western RPG in theme of the three. Despite being the oldest of the campaigns it is not a deserted realm by any means.
* Factions: the second add-on which takes an oriental theme. I can’t comment much on this one as Gameplay are being slow with the package, but it is apparently the smallest of the three and PvP oriented. Again I am not sure yet but this campaign is apparently popular for Alliance Battles, a form of PvP.
* Nightfall: the third campaign, which has a African and Arabian feel. As this is the newest the guild I am in, the Godless (an offshoot of OcUK) seem to exist here the most.
Each campaign can be bought individually but if you have more than one your characters can move between them. The key difference between Guild Wars and traditional MMOs are that the level cap is a low 20, which can be reached very quickly, making it a game more about skill than grind. It also means that some people can get bored of it as there is no urge to level up as you can’t, most people migrate to the PvP side of things, which can be as frantic as an online FPS. Also outside of towns the game is instanced, both a good thing so you don’t have to queue for bosses to spawn, and a bad thing as you won’t wander into anyone else apart from you party. It is definitely entertaining, which I can prove based on that fact I am approaching 400 hours of game time, though I’d say it’s an MMO you’ll either love or hate.
There are two reasons I’d say to give it a go. Firstly there are no monthly fees which means you can pick it up and put it down at your leisure (I stopped playing in 2005, my characters still exist since I started playing again). Secondly the newest campaign, Nightfall can be picked up - in collector’s edition form no less - for a bargain £18.96 on [competitor] which is cheaper than most places do the standard editions.