During World War II in Scotland, a boy finds a egg which turns out to be the monster of Loch Ness, so we have beautiful scenery and music in this movie. I also thought it was quite well-acted.
However, I felt it lacked in the plot department. A movie about this creature could have been so great, but this is basically just a story about a boy and the love he has with his adorable CGI animated pet and how it empowers him. You could substitute a giant mutant slug for the monster, and it would have made no difference in this movie.
It is a sweet film, and I did tear up at the (predictable) ending, but if they could have explored the Loch Ness mystery more and had more fantasy elements it would have been so much more engaging.