I played Guild Wars for about 6 months. It's more of a mmorpg lite game unless you pvp (that's player vs player). Max level is 20 which can be reached in a couple weeks unlike some other games where it may take you months (or even years) to reach max level. Heck, if you want, they will start you at level 20 but you will have a limited choice of skills.
The pvp is quite good if you are interested in a challenge. Pvp matches are team based so find a group of friends either in real life or online.
What is great about Guild Wars is that it rewards skill and knowledge over time spent playing. So you don't have to worry about that level 99 Wizard pwning your level 6 sorry butt since everyone is the same level.
"And so he spoke, and so he spoke, that lord of Castamere. But now the rains weep o'er his hall, with no one there to hear." - The Rains of Castamere