Really difficult to rate this as it is not a memoir nor is it diaries that were written with the obvious intention of publication instead this is an almost daily update about the mundane details of that day. Entries are mainly along the lines of filming x, dinner with x, bought a toaster etc.
These diaries do build up an overview of Rickman‘s daily life but there is nothing personal or in-depth.
Not sure this would work as a book but audio ok.