I haven't read the book, because I have an aversion to fables featuring talking animals (maybe George Orwell is to blame). I watched the film solely because Ang Lee was behind it. The technical wizardry everyone is talking about is front-loaded – the credit sequence at the beginning of the film introduces us to the animals in the zoo, which look both real and animated. I suspect that actual footage may have been involved in some of the shots, which was touched up to resemble the animated shots (the most brilliant of which is a monkey flitting about the branches of a tree). It works because the tale isn't supposed to be realistic – it is framed as a story told by a survivor of a shipwreck. I saw the film in 2D, but Mark Kermode may well have given the 3D version a pass because of this distancing (or 'Brechtian alienation', whatever he wants to call it).
Peter Bradshaw is right to focus on the question asked at the very end – the moment the entire film builds towards, the bit where we are all supposed to start believing in God. Bradshaw thinks the exchange is fatuous, and it is: just because one man allegorises the horrific trauma he experienced in order to move on doesn't mean we all have to embrace a religious life. However, I think the film poses a more insidious question: why shouldn't we prefer an imagined reality if it bestows comfort? Why should we privilege an understanding of the world based on the rational investigation of the evidence of our senses? A Dawkins acolyte may respond by stressing the many comforts brought about by science (something the film acknowledges). But another tack might be to question the assumption that people need an imagined reality to feel content – perhaps some are able to find tranquility without it.