Is the film blasphemous? 50million (and more!) readers of the book worldwide probably don't think so.
Of course it's a sensitive issue and one that is critical of the whole institution that the Catholic Church is founded on. But it's just a fictional story decorated with historical fact. That does not make it "The Truth", but is merely an intepretation of it.
Remember, just before the Passion of the Christ was released there was just as much criticism and commotion.