The book was excellent, and as I remember it, left the central question of the story completely unanswered. I found it unfortunate that the movie has added a short scene at the end which apparently gives a more concrete answer to that question. I suspect this was because the makers felt the audience would be unhappy without some kind of resolution. (I deliberately leave this comment vague, because I do not want to spoil the story for those who have not read the book or have not yet seen the movie.)
Regarding some other comments I have read on this site, the comparisons to Blowup and L'Avventura are very apt, except for the final scene, of course!
Regarding some other comments I have read on this site, the comparisons to Blowup and L'Avventura are very apt, except for the final scene, of course!