Actually as a pally ( I was first a pally before a rogue ) Warlocks are easy to get away from, thats my build, holy/protection, so I can pretty much survive anything thrown at me. But as a rogue, I can kill a warlock with 2-3 hits, the thing here is I HAVE to be cloaked because i get a 10% boost in damage, plus i have to hit from behind with a ambush and thats around 1800-2000 damage and then a backstab, thats another 1400-1600 damage, and maybe throw a eviscerate at the end. I have not tried the cloak of shadows yet cause i love my build right now and it works pretty good. However, if im not cloaked im pretty much dead so its extremely important that you are always hidden, run back and get out of combat and recloak. I count on the element of surprise. Cloak of shadows is getting nerfed though from what i understand, its going to require level 66 when expansion hits.
Here is my build for Rogue
With this build all you gotta do is cloak and then hit a mage or warlock behind with ambush and then another backstab and they are pretty much dead, after that hit vanish, rinse and repeat. The thing i like about this is that you have preperation just in case you need another to make sure the person is dead. You have to be fast though before anyone finds out and puts some dots on you lol. I can kill players right next to their group without them even knowing cause ill be gone before they know it
I love rogues!
Use that build and you'll be one of the first 3 on the list after a game, always worked for me.
Demo video of how it works.