I am interested in pvp this expansion since it isn't so gear biased and only the best pvp players get the best gear.
I think that shamans are probably the worst, all three specs, in pvp. I also hear that resto shamans in WOD will not be the best either, but enhance shamans are pretty good at pve dps.
I don't think it's worth it to be good *melee* dps in order to lose out on pvp, casting, and healing.
Luckily I have a deathknight and can get into raids quickly with tank gear and also do well in pvp without being a squishy weak target that either dies in 2 seconds or cant cast a single spell while not moving