Okay, so, I feel a little awkward reviving this (4-year-old!) topic, but I didn't think creating an entirely new topic was worth it, so...
I put the entirety of
Rosalina's Storybook into an online format, for anyone interested. It contains pictures ripped from the game, as well as has the text formatted the way it appears in game, at least as closely as I could do. I thought the story was lovely and deserved to be put online somewhere.
In response to the topic at hand, I personally loved the addition of the storybook. It was unobtrusive to game-play, yet added a wonderful layer of depth to Rosalina's character, the game, and possibly the Mario universe as a whole.