1st, the content. For most people, a 26 year old policeman marrying a 16 year old girl is cringe worthy material. Obviously one is too immature for the other, and all the problems that come along with dating an older person, not to mention the problems in marriage itself. However, before anyone complains - you know what you are getting into with the story because the synopsis is clear as day. The content should not manipulate your rating because... if you don't like the story, don't watch it. Also, the movie is a Japanese production - this kind of relationship is common place in Japan and not just in Japanese manga. Maybe not marriage, but dating between a 25 year old and a 16-18 year old is normal. Keep the culture of the setting (Japan) in mind when watching.

Now, the story ... The story was definitely disjointed and I only understood and enjoyed it because I read the manga years ago. Large chunks of the story was missing but I was able to connect it together because I remembered what happened between scenes. The actual story (in the manga) is too large and detailed to fit into a movie like this. However, if they had added it into the movie, the movie would have been too boring.

In the manga, most of the story was about
1) Kouta marrying her because he's an officer so he doesn't want to just date a 16 year old girl. He wants to make it all legal.
2) Kako waiting around for Kouta
3) A triangle with Okami
4) Kouta avoiding Kako so as not to sleep with her.
Hence, boring material.

Music etc ... I don't notice those things.

Acting... Well, it was fairly good acting given the story and plot. Not extremely good, but fairly good.

End scene : Happy, but what the hell was that last few seconds?

Watch at your own risk. I won't really recommend it to anyone given the content. You have to decide if you want to get into this. Leave your western perceptions at the door and acknowledge you are looking into a different culture - as we always do when watching another country's production.