1st review here! Just an opinion from someone who had already read a part of the manga, but focusing as much possible on the movie.

- Action scenes, as also the cinematographic are so good. Perhaps certain fights, as well effects are forgettable, but I think they fit very well for the atmosphere of the movie.
- Despiting the cold and quiet assassin archetype Fable representsand, I think he is a very interesting character, and his relationship with Misaki, besides to being cute, gives a good contribution in knowing that human side he has, and more with the memories of all the things he experienced since he was a kid. But outside of that, I don't have much to say about the rest of the characters, especially the antagonist, who is a one-dimensional psychopath, and with a disappointing death.
- Casting is decent, im not so convinced with the actor for Fable, but his performances are not bad. Other actors did a good job, for example Kimura Fumino as Yoko, but as I see, many of they are so secondary, that with the limited time they appear in the movie, i can't say much for it either.
- Some of the most notorious jokes seemed cleverly good to me, taking into account that good part movie is based on parodying the archetype of assassin that represents Fable, while other jokes are so out of place that i think these should have stayed only in the manga, but I think its ok for a film adaptation.

Overall: For me, I would tell you that the 1st you most should give a chance to is the manga, in case it catches your attention. However, its a good movie, with interesting things within the plot and the characters that could be polished better, and with a humor which will not be for everyone, but that gives a good result in what it promises.