Living dead a pain ?
Actually, no, on some situation, it's better than holmgang.

Why ?
Cause you have 10s to activate it, and 10s to heal it.
What that this mean ?
During de 10s your DK activates it, you can totally ignore him and let auto from the boss hit him until walking dead is active. The another 10s (more or less) and heal him 5s before the end.

It's easily dealt by healer with : Excog, Essential Dignity, Benefic II, Benediction.

The only moment I had problem healing my tanks when he was in a living dead moment was when I was out of ressources because everyone died/my co-healer healer as well, mana issue ect...

So, no, it's not a nightmare at all.