From The Guardian: Enhanced ebooks are bad for children finds American study.
Researchers at the Joan Ganz Cooney Center in New York worked with 32 pairs of parents and their three to six-year-old children for the small study, Print Books vs Ebooks, which gave each family a print book and either a basic ebook or an enhanced ebook version of the same title. Enhanced ebooks were found to distract children from the story, and their bells and whistles prevented children from remembering as many narrative details.
Enhanced ebooks should still be valued, however, "for their ability to prompt less motivated young readers toward engagement when they might otherwise avoid text altogether".
This does fit with other analyses I have read about ebooks, that they will complement, not replace, traditional print.