Charon121: Character creation is a huge part of RPG enjoyment for me. I can easily spend a whole day creating the party or just one character. Having the opportunity to create multiple party members multiplies this experience. This is, of course, followed by extensive research on classes and their practical in-game usefulness, since games often have badly designed classes. Some look good on paper, but are simply too impractical or trivial. Some are overpowered and thus render other party members useless. My goal is always to create a balanced party where each character is equally useful, in our out of combat situations. I also carefully craft their personality, inasmuch as the character creation screen permits me, for an enhanced roleplaying experience.
So, as I see it, party creation is a very welcome addition to any RPG. Replayability depends more on the story and the game world, not so much the characters. If I do replay the game, I still use the optimal party configuration.
This is true for me as well. I spend hours creating parties in the IWD games. I usually give them a little personality nugget, so to speak, when I create them and then let them develop as I play, adding to their backstories and personalities and such. But I also DM D&D, so this sort of behavior is par for the course for me. :)
