Just thought I'd drop in some info they announced yesterday that I thought was really interesting and they hadn't gone into too much detail about until now.
First off dungeons - http://www.guildwars2.com/en/the-game/dungeons/into-the-dungeons/
And info on how underwater adventure is going to work - http://www.arena.net/blog/jonathan-sharp-talks-underwater-combat
I've gotta say I really like how they don't have a breath meter, but still explain it away with a breathing device. Not to mention the weapons that are exclusive to underwater combat, like harpoon guns. The drowning state instead of a downed state is also a nice touch.