My main character is a lvl 70 Enhancement spec'ed Draenei Shaman (16/45/0), and I have to say it's THE worst spec for PvP unless you like dying a lot. I keep hearing about the days when the enhancement shammy ruled with killer melee crit nonsense, but the addition of Resilience to PvP gear killed us.
So, everyone's been telling me to respec' restoration or elemental. I'm contemplating respec'ing rseto only because I have a very basic nub healing set. If shaman talent trees weren't so gear dependent, I wouldn't have such a problem respec'ing, but since I decided to level a hybrid class I guess I have to deal with it.