My user testing wasn’t thorough enough be called proof of anything, but I feel confident in describing the results as “promising”, at least. Even the simplest branching story increases replay value, with the children exited to see what would happen if they made different choices. Doing “tasks” while listening to the story did not seem to inhibit story recall.
To my knowledge, there currently aren’t any commercial storybook apps made especially for shared reading on the market, which means there’s an opportunity to stand out.
There is room to take "book-like" much farther from books than predicted. Games like “Burly Men at Sea” are proof that there’s a market for games masquerading as children’s books, even inspiring audiences to share the games with their children. Staying too close to “book-like” sets the user up for certain expectations about how the storybook is supposed to work, that aren’t necessarily ideal for interactive storytelling. For instance the idea that you can turn back pages in a book.
It’s hard to get the secondary device to be more than a gimmick, but it shows potential for some features, especially related to competition and secrecy. Screen size also matters.
To finish with the main question, “is there room for iPads in shared reading?”, I’d say the answer is a resounding “yes”. The positives of interactive media offer great opportunities for engaging interactive storytelling, and It doesn’t take much to overcome its negatives.