My stance on Ret as a PvP spec is it'll be fairly balanced once 5.2 brings the outliers in line, but it's not as perfect as the patch notes indicate. MoP Ret was built around active survivability and the global double nerf to healing hurt that.
-Buff Glyph of Templar's Verdict, which is already mandatory, from 10% reduced damage to 15%.
-Get rid of Sacred Shield's initial internal cooldown.
-Sword of Light, the Ret passive which increases the healing of WoG and FoL by 30%, should include SS. Then buff WoG to ~45% because the damage tradeoff has become too large a sacrifice.
Ret still isn't really wanted for RBG's.
I think Ret needs stuff that promotes it in this sort of environment. For example, Execution Sentence is worthless in PvP. What if, similar to Prey on the Weak, ES increased damage (if cast on an enemy player) or healing (if cast on a friendly player) by 10%? This would probably be Ret/Prot exclusive because Holy is already wanted for RBG's.
By the way, my intention with these suggestions isn't some lame attempt to get my personal ideas implemented, but to give a general idea of what I think Ret needs.
This is more of a fun complaint than a balance complaint, but Ret could use some more talent choices.
-Change Speed of Light to something different for Prot and Ret. How is it that this class's melee specs only have one useful PvP mobility talent (Long Arm)?
-I really wanted Repentance to be good for Ret PvP, but I don't think that's gonna happen. Buff Sacred Shield as I suggested earlier. Unbreakable Spirit is relatively weak in competitive PvP. Tier 75 is okay. The final tier only has one good PvP talent for all paladin specs.