How I Use It
We used it to review skills learnt in a lesson. Each student chose a skill and wrote about it. We then added them all together in a book.
We have also used this to write collaborative stories. We shared the ideas with a number of classes, and they added to the story as it was being written.
This is simple but effective. It does not need a lot of teach time to get it up and running in the class, especially if story writing/publishing is your focus rather than a tech lesson.
They are improving the program all the time, i.e. adding a co-teacher to your library, so I expect to see this getting better and better.