Apparently they did! Let’s start with a general hotfix (*salute*) first.
Secondary Stats
Haste is now 11.1% more effective. What this means is you need 90 Haste rating to gain 1% Haste, whereas before you needed 100. This is a boost for damn near all classes and specs, as it’s pretty much FREE HASTE RATING YAY but the warlock spec it benefits most is Affliction, Haste being one of its best secondary stats along with Mastery. It only really amounts to around a 1% damage boost that everybody gets, but hey! Enjoy it.
Demonology
- Mastery: Master Demonologist‘s effects have been increased by 33%
Whoa. 33% is a large number! Those that play Demonology are saying their Demonbolts hit like crazy now, and Demonology is a very very good turret spec, like Arcane Mages. Thing is, unlike Arcane, Demonology will also be very good at movement DPS, not as good as melee or hunters, but still a lot better than the other casters, so did we just see Demonology become the best spec in the game when you factor in every aspect of an encounter?
It’s safe to say that this is a pretty healthy buff. 10-15% higher DPS some people are saying. Gosh!
Destruction
Ah yes, my spec of choice.
- Devastation now causes the Warlock to gain 15% (up from 5%) of the Critical Strike stat from all sources.
As an example! Raenah, my Warlock, currently has 1006 Critical Strike from her gear. 5% of this is 50.3, which is rounded to 50 and added on to her total to give her 1056 Crit. It takes 110 Crit rating to give a 1% boost, which means Raenah has a 14.6% chance of a crit, when you factor in the 5% baseline Critical Strike rating.
With the new buff, 15% of 1006 is 150.9. I assume this gets rounded up to 151, and not rounded down, making her have 1157 Crit. This converts to a 15.5% Critical Strike chance, which is a boost of 0.9, which is a 6.16% increase from the previous number!
The workings out for those who care?
It’s basically nothing to be too excited about at this point, but as gear gets better and stats get larger, you’ll see more and more of an effect from this buff. Obviously it will boost Chaos Bolt damage slightly too, and higher crit means more embers and better AoEing, but for now it’s still a relatively small boost. We’ll see how well this shines when the gear scales upwards!
Merry (LATE) Christmas, fellow Warlocks!
Panda Steve Types Stuff 
I play demonology on my lock and this is indeed all good news. Awesome!!
I’m currently leveling as destro(lvl93 atm), should I switch to demo?
Personally, I leveled as Destruction and still play it because that’s what I am comfortable playing, that’s my preferred spec. You’ll do best with the spec you are most comfortable with.
That being said, this is making me wanna drop Affliction in favour of Demonology! I’ll still have Destro and will play it most, but I’ll have Demo as the competent backup.
I suppose my tl;dr version is “play whichever spec you like most, you’ll do best in that one” 😀