Elemental and Resto specs still need work/tweaking for pvp viability. Enhancement is ok, and getting better once they get Frozen Power. It's probably the best pvp spec now, good mobility, good damage, lots of utility. Squishiness hardly matters now that pvp is all about burst, and shamans sure can burst. I think for PVE, all specs are currently fine.
I left my shammy behind for a DK though. Effectively, playing a DK now, the class is basically an enhancement shaman in plate. It's got everything my shaman had - spell interrupts, snare, good burst, self buffs, self healing - along with everything i WISH i had - good damage mitigation, a silence, a pull, a USEFUL pet (bah elementals BAH), worthwhile dots and debuffs. I lose out on being able to heal others, but gain the ability to tank. Basically, DK is the class I wanted my Shaman to be.