That info is useful.
Here's some that isn't. At the bottom of each "page", my iPad now informs me how much time it will take to finish the book I'm reading, barring snacking or checking messages (conveniently done on the same device).
Just wondering how "they" know this? From some algorithm that monitors my pace through the ebook? Or is it the average reading speed Apple calculated for someone of my "demographic"?
Moreover, WHO CARES? Possibly some folks choose a book based on how much time it will squander. If so, the system needs an upgrade: this info is only useful before one hits "Download (PAY) Now".
This info isn't just useless: it's harmful. Knowing how much time remains to be lost in a book is like knowing exactly how many hours you have left to stand on the edge of the Grand Canyon. Or be in love. Or live. Isn't it unhealthy to break that spell, just so you can get ready to do something important like send a text or shop online?