If you assemble a staff like Takashi Miike, Shun Oguri, and Meisa Kuroki, you can expect a better than average high school drama.
If the story isn't interesting, the mayhem that goes on the screen keeps things going. It's a mindless entertainment, no doubt about that, but it's designed to cater to certain crowd of people that identifies with this sort of story.
Based on a comic by Hiroshi Takahashi, Crows Zero is about Genji Takiya (Shun Oguri) who transfered to Suzuran Boy's School. The school is the lowest grade high school in the province. The students are all delinquents, but Genji is notch above the rest. Nobody has become the top leader in this high school, but maybe Genji will succeed where no one else have in the past.
The story is definitely not for everybody. But if you understand the plot, it's quite entertaining. Director Miike puts in his usual high quality behind the chaotic directing style that he has.
Just don't choose this movie as a one to watch with your girlfriend on a date.