I haven't read the book, but I did peruse the wiki before I went to see the movie. I actually really liked the ending the movie took and felt it was done in a way that tugged the heart-strings, but also let you laugh at the absurdity of it and grieve with the partner and his daughter. I think (and this might just be me) American audiences don't really like ambiguity and M. Night opted to give a rather definitive answer. We were definitely talking about it after the movie and it gave me food for thought for days, whereas the darker ending of the book probably wouldn't have played the same way (at least to me) and I would have left the theatre feeling cold and empty.