There's already a thread in here on what Mother 3 is and where to get it and bla bla bla, and I don't want to splat out too many spoilers. What am I, Nphyxpedia?
Anyway, to elaborate on my comment about the first three chapters, and this may be a short perspective since I haven't got very far in the main game, but I feel it's bad story structure to spend so much time on background and flavor. A short prologue, 1-2 hours, to introduce some backstory and peripheral characters is cool but I didn't feel like for the time I spent I learned a lot about the world, what's happening, or who these people are.