pizza is incorrect.
edit: i realised my answer could come off as elitist/ignorant and so i decided to explain.
shamans in any spec except elemental is viable. the key lies in knowing where to play and learning the kiting routes. for both elemental and enhancement, you should more often than not just skip the idea of taking down say, a rogue entirely and instead stick to thunderpunting stuff away, running los and hugging a pal. the key lies in the fact that shamans have a higher skillcap than most other classes at 19, and untill you get your focus purge, your kiting routes (to get rid of warriors / paladins which will both murder your face in) etc, you will probably not enjoy shamans. i find it helps to play defensively untill you got your rotations covered, and just purging absolutely everything.
as for the MoP discussion, Pizzas statement implies excessive beta testing on his behalf since we have no way of theorycrafting "what class will be best." all hes basing it on is the totem and dispel which will be irellevant if it turns out that your healing troughput is whack. remember, at endgame, shamans rely heavily on mastery on haste, two stats that are either irellevant or non-existing in our current bracket.