Running comment and annotations on single titles can overwhelm multi-purpose threads and groups. This is the place where unlimited notes on single titles may be conveniently gathered in dedicated threads.
A few suggestions: 1) enter the book's title as the thread title. In case there are other threads about that book but you wish to make your own, consider adding your name or initials to the thread title (also an idea if you'd like to mark your reads in general, or have them collect together if sorting by thread title etc.)
2) Populate the "About" field of your thread with the title, and remember to touchstone the work in order to create a clickable "Mention" on the work page and perhaps draw more eyeballs/more discussion to your thread.