With the coming of 4.3 it has laid to rest the notion that it would kill Arms PvE DPS being competive with Fury, and in fact made Arms the viable PvE spec by a lot. People called me crazy for playing Arms in 4.1 and 4.2 but look at them now all running around with their single 2 handed weapons. The funny thing is that even with full 4.2 gear I am currently putting out more DPS than better geared warriors on my Server and in LFR (yes I know they are normally lazy in LFR). What it comes down to is how I DPS and the way my spec is set up. 1) I know the arms priority system very well for playing it over a year now, and most Fury warriors are still trying to faceroll as Arms, yes it will put out okay numbers, but no where near where it should be. 2) In DS the same as it was in FL the AoE Arms spec seems to be the better overall spec for the dungeon there are a few fights where the single target spec is better but for the over all raid go with the AoE spec especially if you need your 2nd spec for something else (like having to tank because your guild fell apart 2 weeks before 4.3 came out and still hasn't recovered).
Just remember the best DPS priority rotation will look something like this for single target Open w/ Rend - then begin - CS>MS>OP>Slam(Rage<60&MS still on CD)/HS(Rage>60)
and for Multiple Target: Open with Rend - then begin - CS>MS>TC>OP>MS>BS>MS>CS>SS> then settle into the above single target rotation until BS and SS are off cooldown.