“Book to film” — the phrase sounds simple, like traversing two different mediums but the process is more like a change of state. Think of dry ice sublimating into carbon dioxide and the amount of energy required for the transformation. You may get a weak fizzing or a loud explosion before viewing the final product.
Some adaptations are good films but bad adaptations (Blade Runner is off-worlds away from Do Androids Dream of Electric Sheep?) or bad films and good adaptations (Perfume managed to convey the olfactory overload of the novel at the cost of pacing and charactezisation). When a film delivers on both counts (good film and adaptation), readers and movie audiences should rejoice.
Life of Pi is not perfect but it takes the best elements from an unfilmable source text. The main draw is the interaction between Bengal tiger, Richard Parker and shipwrecked boy, Pi Patel . If you thought the apes in Rise of the Planet of the Apes were realistic you will be glad that you are not stuck on the same lifeboat as Richard Parker.