Enhance is fun in pve and pvp, just don't expect to get very far up in ladders or ratings. Resto is definately the pvp spec for shamans if you're aiming high.
Enhance offers great burst every 2-3 mins or so, so quick fast zergs are on their side. Problem is surviving that long or even the first 20 secs of combat.
We are always the first target in arenas, at least that's my opinion. We literally have no tools against stuns except one trinket and no stun for ourselves to give out, and no capacitor totem does not count, haven't seen a player so dumb to stand in that weak ass radius even in the 0 rating arenas, so against warriors, which majority are playing now, cause well op is op, we are doomed unless outgearing them.
Pretty much any class with more than 2 stuns are pain in the ass and lethal to us, which at the moment seem to be nearly every other melee class. With Ascendance clothies go down fast so your best bet is to try to survive the first wave of stuns somehow, with teammates help preferred then popping cds and blasting down healers with purge on the spam, excluding mages, the blizzard favorites. Priests and warriors are reigning one expansion, mages for 10 years. But yeah, your best bets are against priests, warlocks, monks, paladins and hunters.
Having a paladin teammate is half the meal just bop the first stun wave and you're golden then blast away their weakest link pref healer and for the second stun wave, run or die.