I'm not sure whether it was ever a book. It was a Pulitzer prize winning play. Rev. James Martin, SJ was a consultant to the movie (and also the play, I think). He wrote about the experience in his book, "The Jesuit's Guide...."
I found the movie enthralling. In the first place, the acting! Philip Seymour Hoffman, Meryl Streep, Amy Adams, Viola Davis. I was a child in the pre-Vatican II church, attending Catholic school, and every detail and nuance was so accurate. When the children in church sang, "Holy God, We Praise Thy Name," they sang "in-FAN-ette" for "infinite," just like we did as kids. And the nuns with the clickers so we would all stand, sit, and kneel at the same time.
Hoffman was so much the everyday guy kind of priest I remember, talking about football scores in the homilies, just a "regular guy." For a long time after Vatican II, when ordinations were down, it seemed like fewer and fewer "regular guys" were becoming priests. Instead, they often seemed like arch-conservative little hothouse flowers who seemed to exist in some kind of world other than ours. (Thankfully, there are more priests being ordained today, and there are plenty of regular guys.)
I thought it did a good job portraying the suffering and angst and yes, doubt, and the difficulty coming forward with an accusation. It was just true to life--thanks to wonderful acting--and Fr. James Martin.
Being a New Yorker (although we moved to the suburbs when I was 4) I felt all the environmental details were spot on, too.