If you&re interested in film aesthetics, you&ve certainly read one or two books by David Bordwell and Kristin Thompson - "Film Art: An Introduction," for example, is an absolute standard work that is still available today, a good 40 years after its publication, in what is now the 12th edition.
However, some of their books are no longer in print, and in recent years have only been sold as PDFs via their (very readable) blog. Recently, these PDFs are now freely available for download. Among them are "Planet Hong Kong", which describes how Hong Kong cinema mixes art and entertainment, "On the History of Film Style", a look at film history with a clear theoretical slant, or "Christopher Nolan: A Labyrinth of Linkages", which studies Nolan&s style in depth.
We just read into "Planet Hong Kong" and immediately felt like re-watching some of the HK classics - a perhaps not entirely unexpected side effect...