How the build works
This Fury Warrior build is about two things: crit and Rage. Cruelty adds 5% melee crit, and Unbridled Wrath gives each weapon hit a 60% chance to generate 1 extra Rage. With two weapons swinging, that second talent keeps your bar full enough to Heroic Strike far more often.
Dual wielding has two weaknesses, and rows 3 and 4 fix them. Furious Precision raises off-hand hit chance by 10%, and Dual Wield Specialization adds 25% off-hand damage and 50% more Rage from off-hand hits. Blood Craze is a light self-heal (2% of your Health over 6 sec after a crit or a big hit) and mostly opens row 4.
Death Wish, your 21st point, increases your Physical damage by 20% for 30 sec and makes you immune to Fear, at the cost of taking 5% more damage. Save it for elites and pulls that could go wrong.
Leveling tips
Spend levels 10 to 19 on Cruelty and Unbridled Wrath; both help even with a two-hander. Furious Precision and Dual Wield Specialization only make sense once you hold two weapons, so get a decent pair before you reach them.
Fury is the weaker leveling spec of the three. You take more damage and rest more often. One popular plan is to level as Protection until 30 and respec to Fury once your gear allows it. In dungeons, Fury is fine as long as someone else tanks.
Changes in WoW Forever
The Fury tree was reworked in early October. Furious Precision is new and took over the hit bonus that used to sit in Dual Wield Specialization. Lingering Rage and Gore Drinker are new as well: the first delays Rage decay after combat, the second makes your Enrage, Berserker Rage, Bloodrage, Death Wish and Bloodthirst effects heal you for 1% of max Health on the next 3 swings. Improved Cleave and the old Precision talent are gone. Bloodthirst still sits at the bottom of the tree, so it waits until level 40.
When you compare Warrior talents across guides, check the date: some September and October pages still list removed talents.
Toward level 60
This part is provisional. The one complete level 60 Fury build so far is a simulator result: about 31 points in Fury (Flurry, Improved Execute, Raging Blows, Bloodthirst) with 18 in Arms for Deep Wounds and Impale. Players disagree on details such as Lingering Rage and Gore Drinker versus Blood Craze and Enrage, and nobody has tested it at the level cap yet.