I think how much you enjoy this movie will vary based off of if you see it in 3D/Imax versus Standard.
The 3D version was cool, the story is almost scene by scene from the Disney version of The Little Mermaid, barring a few exceptions.
The ending is well-executed.
Was never that into the Disney movie, but even for non-fans of the original Disney movie there are moments that are memorable and make the movie worth watching.