I don't understand why this film has such a low rating on IMDb.

There are a couple of things that could have been improved on.

Firstly is the colour grading. Some of the shots (particularly the external ones) are not well balanced, and often the colour grading does not make sense to the viewer - thereby leading to some confusion about the relationship of one scene to the next or it's place in the story.

Next are some of the CGI effects. The effects are appropriate for the scene, but are not integrated well.

Apart form those couple of things, technically the film is OK and are soon forgiven as the story unfolds.

All of the actors do a good job of portraying the characters, and I felt there was a genuine connection between them in relation to the story being told.

All in all it is a film worth watching, and worth more than the low rating on IMDb.