I appreciate the wealth of information that is accessible by clicking on the book icon when viewing a PDF. I can select among Table of Contents (ToC), Bookmarks, Notes, Information and Meta-Content. DevonThink to Go would do well to mimic this approach for their comparable book icon (which shows only the ToC).
I would prefer to have the ToC tab always show even when the PDF has no ToC. This change would parallel the behavior of the Bookmark and Notes tabs. They remain present even when the PDF has no bookmarks or notes. To appreciate why, consider that I stumbled across the ToC option only by opening a PDF that had a ToC. Otherwise, I would have even now still had no inherent sense that I could find the ToC for a PDF so easily in Bookends.