I've never liked voodoo, simply because you can strike at anytime, from anywhere, and as such there isn't any proper defense or precaution for it.
Yes, you can get ridiculous enchantments that help. Yes, you can keep shield and other spells up 24/7. Yes you can quaff spirit aura constantly (if you're not one of the many many players in religions). Or you can hide in a no magic room (which totally helps stimulate RP
). But the problem, unlike all other aspects of PK, is you never know when to prepare. To be constantly holding up all these buffs and spells in the off chance that the enemy shaman might decide to voodoo you suddenly is kind of ridiculous.
In all other aspects of PK, you know when to be on your guard and when you're doing something risky and careless. Don't sleep in a lightie leveling zone as a wanted darkie. Be careful in Teron. If theres an enemy rogue about, have a pet behind you. If not, have one in front. But no matter what, any other style of PK requires the enemy to be in range, which gives a genuine chance of risk to all parties involved.
And yes, as it currently is, you can retaliate after the fact, by trying to gather and convince allies during the short post-voodoo vulnerability of shaman, to gate and attack; but most people won't be interested in gating into a room full of hostile guards and enemies, which is where any decent shaman will be.
As many have said before, shamans are a solid class without voodoo. Personally, I like the RP of shamans being able to use some sort of voodoo spirits, but not at all like the current spell. If its kept, maybe make it into a regular PK damage spell with a duration affect similar to the "sticking affect" of magma spray. IMHO.