Largely, yes. It ended when it was scheduled to end on every realm (and I'm not just saying that; with the duration it had on the last day there was really nowhere else for it to go from there) and had the impact we were looking for. Did everything go according to plan? Mostly; there was the sanctuary issue, and there are certainly various aspects of the event that could have been further refined, but overall it was a successful venture.

I can't tell you what the future holds, but I will say that we'll certainly keep the feedback from the zombie event in mind should another event like it be on the horizon.

Over all we consider it to have been a success. We have a team that works on world events and are always looking for ways to spice up Azeroth. Whether or not any similar event occurs again though I cannot say. First and foremost, it'd have to serve a specific purpose. We feel the zombie plague fit in very nicely with the coming of Wrath of the Lich King and decided to run with it.

We knew it would get ridiculous and out-of-hand, and we took the negative feedback into consideration. At the same time though, the event was always planned to last only a matter of days, increasing greatly in severity as time passed. So some of the complaints about the interruption of game play were expected in a way, though we knew they'd pass as quickly as the event itself did.

As with any sort of game play features or events we release, there's always room where we would like to see improvement. We're generally always very ambitious with our events and, even if given all the time in the world, probably wouldn't find a way to do everything we want. That said, we thought the zombie plague we ran with was awesome, chaotic, and a bit funny as well. :)

Edit: And what Kisirani said too.