GW2 is really interesting. It's basically an MMO that hates MMOs. When treated as a huge single player or small group co-op game with occasional updates, it's a great experience. The world is awesome and lovingly crafted. The art style is fantastic and the music is great. The main storyline of the base game is extremely hit and miss, and as a disclaimer, I haven't played any of the expansions so I'm not prepared to talk about them.

If you're looking for something in the vein of WoW, you will not find it here. GW2 absolutely despises the idea of a gear treadmill, so vertical character progression is almost nonexistent beyond level cap. Raids were a very late addition (not even in the base game) and a very hesitant one. There is essentially no incentive to repeatedly run a dungeon unless you fancy the particular armor skins available from it. There is no "holy trinity" of roles in GW2. This means no healers coordinating with tanks, no dps doing anything specific to help out those healers, etc. It's just a group of people jumping around doing their own thing and trying not to die. The actual cooperation between players is almost nil, and encounter design is very limited by this foundation.

Truthfully, I think GW2 fails as an MMO, but not as a game. Just do not go to GW2 if you're looking for a WoW replacement.