First of all, I don't think the film has anything to do with Leon or just as much as Besson owes a lot to Cassavetes and his film Gloria, so to speak. I read an interview with the director in which he explicitly refers to Gloria.
About the film itself, I like his style. When I go to the cinema, I want to see something other than what we call reality. I found that here. I was tied up the whole time and maybe I missed therefore a few mistakes. Anyway, it doesn't happen to me too often with a movie, and that's what it's all about.