My first warrior leveled as arms, back in the dim past before patch 1.2. It's hard to explain to people just how bad playing a warrior was back then. We didn't generate rage on blocks, parries or dodges, executes took all of your rage even if they missed, and there was a bug that caused attacks that were dodges to be calculated as misses, causing you to miss out on a ton of overpowers. Berseker stance used to grant 10% melee haste, but no one really knew what that meant. (I wonder if warriors today would trade 3% crit for 10% faster attacks?) I managed to get him to 60 mainly through instancing with friends/guildmates. (To be fair, I was ahead of most of my guild, with the exception of a couple of hunters who'd started playing before I did.) So when I created a new warrior on a new server to play with some real life friends, I wanted to do things differently.
And so I went fury. Being the stubborn cuss I am, though, I didn't level fury with a dual wield build... I didn't like the way I'd miss so many attacks and at that early stage of the game there wasn't much I could do to prevent them, so I stayed with my beloved 2h weapons. I still remember when I got the Relentless Scythe and started to really understand how to output DPS with it. While most warriors were carrying Arcanite Reapers around, I was tweaking my gear for AP and crit and trying to figure out how to squeeze the most DPS out of a two hand weapon (although I also had a pair of Bone Slicing Hatchets enchanted with +15 agility to annoy my wife... as a hunter, she found it irritating that I got them before she did, and I did enjoy using them) - amusingly, just as dual-wield specialization was coming into the game, I was getting into raiding and the guild I was in didn't need a prot warrior, just an off-tank for various MC mobs. I picked up a Draconian Deflector cheap off of Drakkisath (he was very slightly dead at the time, he got better) and headed into Molten Core - you could tank as fury in those days, and I did.
This is where I first learned about ability rotations. We didn't call it that, we just talked about what abilities to use and when to use them. One of the grizzled old veterans of the guild, who'd come to WoW from a seemingly endless list of older MMO's, would constantly debate the benefits of Whirlwind over Heroic Strike, was a firm believer in using Cleave due to the lower threat it put out (he was wrong about that, I am told - Cleave does more threat per damage than Heroic Strike, 1.8 threat per bonus damage vs. 1.1 threat per bonus damage for HS, unless the Cleave hits multiple targets and thus spreads out its threat. There are also factors based on how good your gear is which can make Cleave the better option, but at this point my eyes start to glaze over) and scrutinized every change to Bloodthirst with the keen eye of a jeweler, only he wasn't flaking small chips off of a diamond so much as chopping huge chunks out of a Molten Destroyer. When Patch 1.6 came out and we all had to respec, three of us stayed fury and became a sort of sub-clique debating how to best increase our damage, always trying to fight with the rogues for top DPS (ah, Suppression Room, how I loved you).
Fury's changed a lot over the time I've played the game. Patch 1.12 changed it even more by introducing 41 point talents in all trees. For fury, the top talent became Rampage, an ability that can provide great situational benefits in PvE but is less impressive in PvP, where it's hard to get people to stand still and let you build up five melee hits to maximize the effect. Still, the basics of fury DPS in raids and instances remains the same: do as much damage as you can without overcoming the tank's threat. As a fury warrior, you have the least armor of any warrior, you've most likely tweaked your gear to maximize your hit, AP and crit chance over stamina so you can take the least amount of abuse, and you have no aggro wipe or dump outside of the inherent threat reduction of Improved Berserker Stance. You cannot feint, cower, disengage, feign, ice block, or fade, and you shouldn't need to.
Changes to abilities like Whirlwind (allowing it to hit with two weapons) and adding Sweeping Strikes to the fury tree have changed some aspects of the spec. Whereas back in the day I offhanded a fast weapon and main handed a slow one (lots of other fury warriors did the exact opposite), now you might well go with a slow/slow combination to maximize the damage of your offhand hits on the instant attack of Whirlwind. Weapon speed and indeed weapon damage don't really matter much to Bloodthirst since it's based on attack power (which you will hopefully be keeping steadily ramped up with Rampage) so you really only have to consider the weapon speed for Whirlwind, meaning that the change to the ability really calls out for a big slow offhand to overcome the damage reduction for an offhand weapon. It's worth taking at least a point in Improved Whirlwind to reduce the cooldown on the ability in order to more easily fit it into a rotation. Before we really get rolling, let me point out a good DW guide for fury and a 2-hand weapon guide that covers slam, both from Tankspot.
For dual wielding, I'm now generally in agreement with the Tankspot guide that you want roughly 95 hit rating. (My fury gear actually has more, that's just how it worked out... I tend to swap in some stamina pieces to try and get down to 95 when it doesn't hurt me too much on AP and crit to do so) It's important not to miss with your specials, but a few white misses aren't so huge a problem that you should be reducing your Strength and critical hit chance.
For an ability rotation, you are ultimately the best judge of your gear (I can't come to everyone's server and check out what they're wearing) but if you have sufficient hit and AP, and the recommended point in Improved Whirldwind, then you can rotate Bloodthirst and Whirlwind to good effect. When Hamstring could benefit from Windfury Totem, most warriors used it to the point where it was actually called Spamstring, but now that it doesn't it's up to you if you want to try and proc Flurry and Rampage with it or use Cleave or Heroic Strike instead. I personally use HS when I'm fury, unless I'm really nervous about threat, in which case I don't use any of them (I'd rather have more rage and not spend it than pull aggro off of a tank) but some warriors are very talented at knowing how to stay at about 99% of a tank's threat. I admit now, I'm not one of them. At any rate, aim for rotating Bloodthirst and Whirlwind, using the global cool down for an ability like Cleave or HS when you're peaking rage (since a full rage bar essentially wastes your rage generation) and keeping Rampage up as best you can.
For two handed fury (I know, you don't believe it exists, you probably don't believe in Santa Claus or the Loch Ness Monster either, you grinch) the cornerstone of the build is Improved Slam. To be fair, a lot of PvE MS builds also use it. Some fury builds go up to 40 points in the tree but abandon Rampage in order to get Death Wish in arms, due to the fact that Improved Slam is a rage intensive ability and trying to keep Rampage stacked can be difficult while using it. Using the Imp Slam build (talenting your slams down to .5 seconds) means, paradoxically enough, that you will most likely refrain from chain casting Slam. While a channeled ability (and one that cannot be interrupted) it does both reset the auto swing timer and also sets the global cooldwon in motion, meaning that you cannot use another ability linked to the GCD for 1.5 seconds after casting even Improved Slam. You would therefore rotate a series of talented slams per auto swing timer, alternating them with Bloodthirsts and Whirlwinds. You would effectively have an auto attack followed by a slam, then a bloodthirst, then an auto attack, a slam and a whirlwind, then back to the bloodthirst rotation. In a 21/40 build you won't be using Rampage, whereas if you go 20/41 you would be... if your gear is good enough and especially if you have a shaman in your group for Windfury Totem, a 20/41 slam build can have the potential for vast, vast damage, but it's not a spec that's particularly easy or intuitive. (It's essentially the grandson of the build I used when I first got my Sulfuras, and on fights like the Twin Emperors my DPS would very much suffer.)
There's so much more we could discuss about fury DPS and rotations, but these basics and the links provided should help answer most starting questions. It is my opinion that fury is the most intensive spec of any DPS class in the game, requiring quite a lot of gear tweaking and consideration to get right, but when that work is put in the damage potential is enormous. I've watched our fury warriors and been very impressed with the damage they can do without pulling aggro off of me, and once I have enough gear for it I plan on trying out a few variant fury specs, especially the slam build.
What can I say? You can make a warrior tank, but you can't take the rage out of the equation, and fury spec is the purest manifestation of how the rage mechanic translates to visceral impact. And nothing I've ever done in game, cool as a lot of it has been, has ever made me forget whirlwinding in the suppression room.
Next week - more detail on fury and arms DPS in PvE.