Pallies are overpowered in solo PvM.
No other class can do what they do... I personally have a vid of a pally fighting *four* mobs one level below. He kills two, gets another add, then finishes off the remaining three.
No other class can do this.
Pallies are semi-balanaced in solo PvP.
While it's true they will destroy many classes one on one every class is *not* meant to be balanced against every other. Pallies are weak to being kited, mind controled etc. An experienced hunter should have no problem taking down a pally.
Pallies are underpowered in high end groups (PvP or PvM).
Without decent DPS they can't hold aggro and tank. They cannot substitute for a priest due to weak healing. In group PvP the players have no reason to target the Pally till last due to relatively weak heals and low DPS. Auras/seals/blessings are not as good as other classes buffs and do not justify a slot for the Pally in an instance run.
People who do not play pallidins only see their strengths.
People who do play pallidins only see their weaknesses.
FYI My main is a 46 rogue.