It's a racing genre in the loosest sense of the word. There are "cars" and there is a race, but other than that it has almost nothing to do with the racing genre. The FF comparison is fair I guess, but Redline is so much better in it's execution.
As @Malcador said it's mindless fun, I would add that it's absurd in a great sort of way. But I would say if you don't like the animation style then skip it as it's a big part of it.
Btw, this movie tanked Takeshi Koike's career. He went so over budget and the deadline that no one is willing to trust him with a project anymore.
One of these days I will suggest something that you guys will like.