I was drawn to this as my friend is a player and has given it rave recommendations, I can understand why. Gameplay is balanced, graphics - though slightly dated - are good and some of the environments are incredibly well done and although you can play through the lengthy story missions/side quests on your own, the game has set out to make it far more fun and beneficial if you are with other players. (Many of which are genuinely helpful and will go very much out of their virtual way to help new players)
I have heard this being constantly compared with WoW, I have played both (the latter on a free trial) and although WoW has far better initial visual customisation for your character (I'm assuming a new guildwars player won't want to shell out for all the expansions to improve upon this), I find the game play to be far more varied in GW (no tedious repetition of killing umpteen billion minor enemies to complete quests) and the players tend to be a more friendly bunch.
The controls are intuitive (simple WASD for movement and hotkeys for different menus), the item system is well implemented and one of the more surprising features is a working economy (items gaining/losing value as more/less are available or in demand.) Emphasis is put on skills your character has as opposed to time spend on endless levelling up (a well set up level 14 character will make short work of a level 20) which makes for far more rewarding gaming.
My one complaint is the laughable vocal-acting in some of the story-cutscenes, but considering this is a relatively minor thing...and the game does go at great lengths to not take itself seriously in various NPCs and dialogue.