People in beta are still not listening to Blizzard -- they are level 82, trying to do 83/84 zones. Blizzard has stated in blue at least a dozen times, finish most of the quests and level up before you move on. They expect players in full icc gear to be getting destroyed at level 83/84 if you are not using level 83/84 gear.

Most players don't listen or follow this, so it's hard to judge the true difficulty of the zones.