well, it changed to the point that shaman is one of best healers if not best at the moment. Resto stack healing is strong, but right of now, Resto shammy can get into any fight without any problem. Stats prio - well, depends on what you want to raid, 10 or 25? At least in ToT times, on 25 man Mastery was the stat you wanted most, on the other hand in 10 man, strong haste cap - crit after, and keeping yourself above 50% mastery is a must. Compared to Cata, not really much more changed, oh wait Resto has 2 more Cooldowns compared to Cata - that in SoO are esential and makes them strong
)