Okay, so you have some new skills, some new abilities, and some old ones (Thunderclap & Taunt) have gotten buffed, big time. Threat has been revamped as well.
The big question is, what does this mean?
First off, as a warrior, you can now AOE tank, and you can AOE tank WELL. Really, really friggin well. Warlocks cackling with glee well. Now, the question is, how do you open up against mobs to get maximum threat for that AOE to open up early?
Here's my (current) aoe threat rotation:
4) step backwards to organize the mobs & shield block
6) Shieldslam the primary target
The mobs should be glued to you after that. Obviously, there are some exceptions to that rule. Just do your tab devastates, revenges, heroic strikes, and hit T-clap whenever its up.
Now, the major issues with this?
-Druid trees: I love them... but they are slow. Mom-taking-you-shopping slow.*
Make sure they are standing up next to you before you charge, else, they will be waddling up to heal you (because you charged out of range) and you might go splat. Okay, so that goes for all your healers, but you get the idea.
-Charging the correct mob: Be aware of which mobs are casters and which mobs are melee. Its easier to move a melee than a caster so if there's 2 melee and a caster, try to charge the caster. Oh, hey, and don't worry about the melee running up to you if you get within their aggro range before you can charge... you do know you can charge in combat now, right? ;)
Part 2 will be on single targets, and getting used to the new taunt and charge.
*Mom-taking-you-shopping slow is the pace at which, when you're 13, your mother picks out clothes with you simply wanting to get the jeans, put them in the cart and leave. Its a sunny Saturday, and you want to be outside, but, there's now 17 pairs of jeans to try on. Its summer. You don't even need jeans.