I read widely from many genres. Perhaps this blog will feature fewer ratings and reviews, but I certainly intend to write about my reading life - it's the subject I most find myself wanting to talk about.
One of my reading rules is "Always Read the Book First." I follow it most of the time. When I don't, it's usually because a) the book is not readily available to me, and I really, really feel I must see the film; and b) (more likely) I didn't know the film was based on a book (although in the age of imdb, that's much less likely than in earlier years.
Films are adaptations, interpretations, and collaborative efforts. This necessarily means changes from novel to film, and I am reconciled to that if, a) the resulting film is coherent in plot, characterization, and theme, and b) the changes don't seem arbitrary and unnecessary.
A brief example:
Matthew Quick's novel, "Silver Linings Playbook" -- I enjoyed the book (read in anticipation of seeing the film), although I wasn't always convinced in the way the main character's disease manifested (would he really have such long gaps in memory? such childish thoughts and illusions?) There were significant differences from book to film (a few did seem somewhat arbitrary), but the film had a coherent theme, characterizations, and plot, and it all added up successfully. I'm not sure it will become a classic for the ages, but it had some awards buzz and earned Jennifer Lawrence an Oscar. I was able to overlook the changes and enjoyed both book and film.
On the other hand, I read Mark Helprin's novel, "Winter's Tale" in anticipation of this year's release of a film adaptation. Long thought to be completely unfilmable, the novel is a tour de force of fantasy and utterly engrossing. I found myself thinking, again and again, "what the heck did I just read?" -- in the best possible way. The director/screenwriter got around this problem by focusing on just the story of Peter Lake. But even so, only a few character names and details remain from the original novel. And what did make it to the screen was a barely-coherent mess in which theme did not evolve but was explicated and then pounded into the viewers' heads. Most of the plot was made up out of whole-cloth, not borrowed from the novel at all. Even some of the characters came out of nowhere - whaaaat? Will Smith is the Devil? Maybe so (ha ha), but where was that in the 500+ pages of Helprin?
I will re-visit this topic in the future, but I'll close here with one last example: Kaui Hart Hemmings' "The Descendants" was both a fine book and excellent movie (Alexander Payne never fails to impress). The film is a very faithful adaptation - aside from the usual deletions and condensing of action from the novel, very little was changed. But one major change was the name of the main character's wife. Now that was an arbitrary change with absolutely no discernible purpose.