We played a game of Spirit of the Century last night. It went well, and I can see why the game has such a reputation.
My preparation comprised basically just noting down a few random ideas for a plot inspired by some of the character aspects, and this was plenty. In fact, I had to cut the final scenes short as we were in danger of running over time.
No more detailed issues came up - it's clear that the first few sessions will be slower, as people get a handle on how aspects work and what their stunts do. I expect that each following one will go notably smoother.