Even though writing in Guild Wars wasn't stellar, it did deliver (at least in Prophecies) a story that was fun to follow and rooted in classic fantasy. Personally, I especially loved the cutscenes showing your party members and yourself interacting with the other characters. The writing quality did go down with Factions and onwards, but still, it was somewhat descent.
Now with Guild Wars 2, I have reached level 80 on my main character in september, but I still haven't brought myself to finish the story. The writing is no fantasy, reeks of political correctness (gay trees, fantastic !), and the cutscenes set inside the beautiful game world have been replaced by awfully acted dialogues in front of a boring background. Who's idea was it to remove everything that worked well in the previous games ?
And the biggest problem of all, is that for the most part of the game, you do not feel like a hero, it is not YOUR story. You are commanded around by some dumb treenager, it simply doesn't work for me.
The biggest problem I have with underwater combat at the moment, is how long it takes to kill a mob. If they reduced the monsters hit points, it would make things a bit more bearable. And I feel the same goes for dungeons, basic trash often takes too long to kill, its just not fun !