Definitely one of my favorites!
There are so many creative and innovative ideas and genuine rip-off's of clichés. A real fun to watch. And the stunning art style ... never seen a so detailed and thought-out flick like this one. Even when you watching this film a second time you still might get lost in figuring out all these details.
Music was also perfectly used; a 100% match with the art style (something like Rock/Pop ...(?).. well, you'll get it when you see it) Even the slower and moderate background music (simple piano chords), which was used in the middle of the film for quite a long time, was also a consummate choice.
The highlight, alongside the art style, of this movie was definitely characters and acting. Every one of them really stand out. Some of the reviews complained about a cliché-kind of presentation of Vinnie Jones. You know, this was intentionally; hinting at the cliché image of Gaikokujin (foreigners) in japan. It is just an amazing performance of the entire cast.
If i happen to see this movie presented in an art exhibition, i wouldn't be surprised at all. A real masterpiece, though some might only like it, but not love it, as i do ... well, too bad! ;)