I would recommend watching this without drawing any comparison to its parent story midnight runners, as Japan has its own way of representing a story and also it has been extended into a drama.
It was quite a watch every weekend. The duo was good, had fun watching their comic scenes. Few cases were interesting as the story unfolds. Loved the cameos.
Still, there was something missing that failed to hit my spot. It could have been more engaging. I was quite disappointed with the ost. Most of the Japanese dramas are known to create a single ost for the entire drama that turns out to be quite awesome and just get engraved in your mind. But I wasn't happy with this case. (just my personal preference)
Rewatch value is quite low for me as I already know how the story will unfold.
Just enjoy watching Kai kun and Jiro chan...