I feel that the biggest flaw in retribution playstyle (pvp-wise) is its definition as a support damage dealer. This persona is greatly skewed with the fact that damage has to be greatly sacrificed for healing.
I feel that for retribution to be pvp viable, something needs to be done to allow WoG to be more viable for less holy power. There's a reason the tree is almost non-existent on beta in lieu of overpowered protection and holy trees.
I believe that the talent 'eternal glory' should be moved into deep retribution (or some form of it) to allow retribution to either cast WoG without a holy power cost or be able to get the full benefit from the heal without generating the full holy power.
If this change would be flawed (which it would), I'd say make retribution less RNG based (I know everyone's said this a billion and one times but it can't be stressed enough). Remove divine purpose or revamp it to allow other abilities such as judgment to generate holy power (as in 100% chance to do so). Hand of light mastery, as great as it is, is just one more RNG based ability in the retribution arsenal. As it is right now retribution is ridiculously weak without wings up. Changes need to happen.
For the talent itself, its an amazing idea but being balanced around how well you can heal others instead of how well you can heal yourself is absolutely silly. WoG heals for ~12k at 85 in full pvp ret gear. This is far too low of a heal compared to how much damage classes are doing. Selfless healer, though it might go against the name, needs to increase the power of the heal on the paladin himself as well.