Reviews of ebooks
That would be a good example. There are so many printed book versions of War and Peace, and it is frequently unclear which version the ebook is based on. In addition, the amount of 'preview' provided, especially by Kobo, is limited, and sometimes not enough to find out what the body of the text looks like. I recently bought an ebook copy of a translation of the Iliad, only to find out that the layout of the eBook is completely different to the printed version of the same translation published by the same publisher. The 'preview' showed only the introduction and list of contents, but not the body of the text.