dont listen to any of the toxic people on this thread (@jaimex)
dno - it will take a long time to get really fluent as it, but for me and a lot of other people rogue is definitely the most rewarding class to play in a game
It's only rewarding when you get that clutch kill, but GL vs hybrid teams. Rogue just takes time to learn, you have to be very attentive. Between combo points, energy, kill target, focus target and partners it starts taking a toll on learning. This is why most people switch to an "easier class".
RLS (Assassination, Destro, Resto) - Works pretty well (2k w/o skype, but that was before my partners just stopped logging on at the beginning of the season). I also tried Boomy/Rogue/MW as well after I was fully geared; that went really good. Started from 2k rating to 2300 with that. I also do a lot of triple dps for fun (boomy/ret/hunter,rogue,warr) - the trip dps part killed my rating vs TSG's (huge amount of those around 2k ratings lol)
Thing about assassination, it's like a mix between afflication lock/warr. So much dot pressure/dmg output (energy based since mutilate eats up your energy), while you have a destro lock/boomy behind you pumping more damage. I normally save my burst till after all defensives are down since you really don't need to use them in the initial openers as assassination. Over time, Deadly poison damage just does absurd damage. You can say assassination is a dampening spec as well.
The only thing about assassination is it's hard to find players that will want a rogue, especially as assassination. Personally, the break point for assassination rogues in arenas is probably between 2200 - 2300. It does really well vs caster teams and plate teams. I've had issues with teams such as Mage/Hunter/X and LSD. I'm positive there are better rogues out there that can play the spec better than I can at this point and I would love for them to push the rating to it's max.
Expose armor is still good as a combo point builder. I still have it on my bars since it's really low in energy and it's 1 cp per use. You don't necessarily have to use it (I rarely do, mostly to get Slice and Dice up if I didn't envenom in time[I'm Assassination]), but if you're low on energy, and need cp, it's pretty decent mechanic to spam to get a few points.
Alternatively, you can use hemorrhage to gain the extra cp's (deals dmg and it's 30 energy vs 25 energy that expose armor has). IT all depends what spec you will be going.