So what's HaT?
If you haven't heard of the latest fad in Rogue specs, allow me to explain the Honor Among Thieves (HaT) build and playstyle. Using a build like this one, the HaT Rogue focuses on one thing: Eviscerate. Glyph for Eviscerate, Improved Eviscerate, and Aggression are all core to to this build. The synergy between Blood Spatter and Serrated Blades also improves your Rupture's viability; a Feral druid's Mangle helps too.
Every time a PARTY member (not raid) critically strikes with an ability (not white swing), you gain 1 Combo Point (CP) on your current target. This includes your own personal critical hits, acting as a sort of pseudo Seal Fate. It's actually better than Seal Fate as I have observed CP being generated from my Eviscerate crits as well. Each party member can contribute 1 CP per second to you, and this number includes pets as well.
But isn't HaT bugged?
HaT is currently "bugged" as you may have heard. For every HaT Rogue in a party, each HaT Rogue gains an additional CP per critical strike. So with 5 HaT Rogues in a party, if any Rogue crits any special attack, all 5 Rogues get 5 CP. Considering that HaT Rogues are amongst the best HaT generators themselves (Eviscerate has a higher than 50% chance to crit on every GCD), you guarantee yourself 5 CP per second at all times. Even if all 5 Rogues were completely naked, the talented and glyphed chance to crit of Eviscerate is enough to keep all 5 Rogues spamming it for the entire fight. Simply stated, a critical Eviscerate from one Rogue generates 25 Combo Points instantly. This is the "bug" that you will hear Rogues talking about. However, with 1 HaT Rogue per group, it is NOT bugged and completely viable. Blizzard has confirmed that the mechanic is working as intended with a Solo HaT (SHAT) Rogue in a party.
With 4 BM Hunters in your party, you could theoretically generate 8 CP per second without ever using a CP-generating move. Now you see why Sub Rogues just can't get enough of our mail-clad friends. Both Hunters and their sidekicks have high crit chances and 1 second Global Cooldowns. This makes them ideal for HaT Rogue party members. If your party can generate enough CP for you to have 5 CP on every Global Cooldown, then you can actually match the performance of a group of bugged HaT Rogues. Exploiting the bug simply makes it simpler to achieve the ideal goal of 5 CP per second at all times.
So what do I do with all these CP?
Provided you are getting enough CP per second, a typical HaT rotation is: Slice and Dice (SnD glyph helps but is not required), Rupture (with Glyph of Rupture), Eviscerate, Eviscerate, Eviscerate, Eviscerate, Eviscerate, Eviscerate... Due to Relentless Strikes (RS) returning 25 energy on most of your finishers, and the 1 second GCD, you can regenerate the full 35 energy for an Eviscerate while spamming it as often as possible. If you use a finisher at less than 5 CP, you risk losing your RS proc and losing energy from your rotation. I would recommend Eviscerating at 4 CP if you have it available, as the chance of getting RS proc is still very high and you want to maximize your number of finishers per fight.
The two biggest concerns in a HaT rotation are ensuring that you never cap out on energy and that you never cap out on CP. With the 1 CP per second per party member limitation in place, your CP generation should generally not outpace your ability to use these CP. However, as the generation is outside of your control, sometimes you will waste CP by having 5 CP but not enough energy to do anything with them. I suggest keeping your energy between 50 and 65, as this allows you to have some flexibility if you lose a Relentless Strike proc you still have some energy in the tank to pump an Eviscerate.
Rebind your keys
It will take even the most apt Rogues a few boss fights to truly control this build. It's very different from every other Rogue build you've experienced, and will likely require some rebinding of keys. I recommend SnD -> Rupture -> Eviscerate being bound to very easy keys like 1, 2, 3. With all the Evisc spamming you will be doing, you'll need it to be somewhere convenient.
Weapons and poisons
For weapon and poison choices I recommend two fast daggers with Wound Poison on both weapons. Daggers are preferred as then your Eviscerates can take advantage of the 5% crit from Close Quarters Combat. Wound Poison drastically outperforms Instant Poison in the absence of Improved Poisons, and Deadly Poison is useless as it won't stack quickly enough to repeatedly Envenom. Feel free to make the "hemo daggers" joke now. With decent party members (Fury Warrior, Ret Paladin, Unholy DK, BM Hunter) you won't need to Hemorrhage at all. I use it solely for starting my rotation if I am the first one to a target.
So why isn't everyone HaT?
HaT is not without its weaknesses. The key issue is that without party members to generate CP for you, HaT vastly underperforms when compared to nearly any other spec. It's completely non-viable in any raid environment without 4 other people in your party. The quality of your CP generators determines whether you are competitive or simply amazing. On fights like Loatheb, no other class can hope to even approach a HaT Rogue's damage; the 50% crit chance buff from the spores ensures that your party's CP generation will keep you spamming Eviscerate. Certain raid compositions and encounters are not very HaT friendly, and so knowing your group and your environment are key to making wise spec decisions.
In conclusion, deep sub hemo daggers using Wound Poison on both weapons is currently one of the best specs in the game. Usually that sentence is reserved for only the most sarcastic of troll posts on the Rogue forums; but today the old joke has become fact. I guess this is proof that Blizzard really does read our threads and take them to heart. If only they'd listen to all the complaining about Vanish...