Le petit Nicolas, is the story of a little boy like any other who is "almost always wise" and that the mistress "the coolest in the world." It literally layer on paper his ideas giving fairly comical phrases ("Dad told me he was tired, but whatever name, in the end").
Beyond his writing, Nicolas describes with childlike eyes of human relations that escape him. Therefore proofreading by adults is just as pleasant.
In the end, a series of small story with a surprising still fall, which 40 years after their publications are published daily album.
For cons, I feel that the drawings are recent Sempé: those unpublished, have the impression that the septuagenarian designer has the least assured brush.