I've always been a chronic respeccer - it's fun and for the price of 4.5 dailies, you get to play a different level 70 paladin every day if you want. I levelled ret all my paladin life and was playing ret pretty well while doing quite a few Karazhan raids and heroic runs. But over the last two months I decided to give the other disciplines a good go-at, and in the mean time build up my other two gear sets. After those two months, I dusted off my good ol' ret set and put the pew pew talents back in play... and boy is it nice to be back in Ret!
Anyway, through my two months of talent waffling, here are my humble findings:
1) Paladins are true hybrids - owning three good sets of gear (holy, prot and ret) is the bare minimum for any paladin. My ret set is my best, but I have fairly decent prot (libram of repetence, uncrittable, 90% avoidance) and holy (+1300 healing) sets as well. I'll be working to get em all updated all the time.
2) Respeccing is awesome. Don't commit to just one discipline. Learn em all. You'll never know when each one is needed for a raid and don't be so proud as to say you won't respec.
3) Retribution is just plain fun. After weeks and weeks of yawning through long, drawn-out AOE kills (prot), or staring at healbot all instance long (holy), it is just plain good old-fashioned fun to see BIG FREAKIN NUMBERS when you beat down on something.
Anyway, I respect all the other disciplines and I will gladly switch to any of em at any time, but in my book, Ret still rules in the fun-to-play category!