my paladin is level 22 atm, and imho, retribution is junk. A higher level paladin recommended following the protection path up until the protection aura (which is really nice btw), and then filling in the holy abilities. No points in retribution I think. ANyway, I took his advice and (Agh!) spent the money to unlearn my talents and rebuild it that way, it's great.
But then, it may just suit my playing style, so you have to decide for yourself. Whatever you want to do, I recommend planning ahead and having a strategy of what talents you are building towards, otherwise, you end up making some weird decisions in the heat of the moment....
best of luck!