I prefer reading it in parts - but posted regularly.
The time between each segment shouldn`t be longer than a week.
I don`t like it that much if all parts of a story are posted simultanously, although it still beats a cliffhanger
Anyway posting in parts makes you think more about each segment and this way you can tell the author your thoughts and he can decide if he can use your advise for his story or something like that.
Hope this answer satified you
sunshine