My Take
Love all the different characters and setting possibilities (with the full version ... you get one set for free and then can buy new sets one at a time or with the pass). It's got a nice story structure framework inside the app to help keep kids on track. I would still have them do prewriting outside of the app just because that will keep them more focused. The only thing I wish is that the completed videos were not locked into their particular channel. I would prefer to be able to do whatever I wanted with completed videos ... post them to a teacher or school webpage. You lose a bit of control when you have to rely on embedding, especially in this day and age of so much being "blocked" by school filters.
How I Use It
Depending on what character/setting set you have this can be used in any number of ways ... the kids telling short stories, explaining a real historical occurrence or scientific breakthrough, or as a "book report."