I think what makes playing a Paladin so difficult is that often players don't really want to play a Paladin at all. They want the abilities; they want the status of the knight in shining armor, but they don't want to play the code of honor (however defined). The honor is seen as an obligation imposed for the abilities and the DMs definition of what that honor needs to be then comes across as a sort of hard ball. What players ought to consider is the notion that playing the Paladin's Code of Honor is a fundamental part of the character. If they don't want to play that, if that isn't literally part of the reason for playing the character in the first place, then they should probably look elsewhere. Once teh DM and the player fall to conflict over the code (with the player trying to minimize it against a DM seen as more strict) the player is bound to lose and/or fail to enjoy the games. I usually try to communicate to my players what I will expect up front. If they aren't prepared to meet those terms, they should play something else.
I also think that a Paladin's Code of honour should be key to some role playing rewards. If a player does a Paladin right, his order can become an asset and he may receive benefits for his conduct. If a Paladin is disgraceful, then he gets what he gets only by his own wit, and he will receive no help via his gods. Anyway, to the degree that the code of honour might be seen as a role playing liability, it can become a strength through rewards for faithfulness. But once again, the key is accepting the code and adopting it as a positive feature of the character. Once a player begins to think of it as merely an inconvenience, the Paladin is doomed to become a miserable experience.
I also think that a Paladin's Code of honour should be key to some role playing rewards. If a player does a Paladin right, his order can become an asset and he may receive benefits for his conduct. If a Paladin is disgraceful, then he gets what he gets only by his own wit, and he will receive no help via his gods. Anyway, to the degree that the code of honour might be seen as a role playing liability, it can become a strength through rewards for faithfulness. But once again, the key is accepting the code and adopting it as a positive feature of the character. Once a player begins to think of it as merely an inconvenience, the Paladin is doomed to become a miserable experience.