how Kindles replicate physical books is very subtle. Kindles do not rely on material aesthetics in quite the same way many skeuomorphs do. The design is underpinned by typographic and layout conventions (e.g., position of page numbers, chapter name and so on) allowing the aesthetics of the UI page to recede for the reader to become immersed in the author’s word. This is a quality any good book designer will tell you the design of a book should facilitate: uninhabited reading.
Unfortunately, the iPad book app doesn’t achieve this level of sophistication. It’s much more theatrical (as someone probably felt the need to take advantage of that fantastic color screen). The app employs elements like an overly-rendered paper texture and a faux page turn animation, which make it difficult to become quite as immersed in the prose of an author as the Kindle’s eInk design allows.
In many ways, the iPad book app was designed to look like a book, whereas the Kindle was designed to feel like a book.
Very good points that relate to more than just Kindle vs iPad design. Too many 'brilliant' and 'cutting-edge' designs sacrifice users' goals and purposes at the altar of looking good over being good for those using them.