This is something that I've been thinking about for a while.
I don't think I quite like it. I feel that playing an MMO should be about social interaction. It's a multiplayer game, having a personal story seems rather unfitting. I understand that GW2 is a separate game from GW, but I really miss the co-op storyline adventure. It was lengthy, challenging, progressing, and was an absolute blast to play with a group of nice players. From what I've played and seen, this new storyline feature does not promote cooperativeness at all. You cannot progress your character through another player's storyline, you don't even get the rewards as a party member. It's built to simply help out a friend once in a while.
And wasn't the goal of a personal storyline to give choices? When I do get the rare chance to make a choice, they are rather meaningless.
In GW2's defense, I have only played so much of the personal storyline. But from first impressions and the 1-15 storyline, I am not enjoying it all too much.
I hope that maybe this will be the general conscious and that future expansions will be much more cooperative than single-player.