Once the gadget is set to work, everybody in school immediately liked Nobita. Thus he got what he wished for, or so it seemed. The device, which had a mind of its own, did not stop at making Nobita popular at school, it continued to boost his popularity to ludicrous degrees. Eventually he became so popular that he became a national figure and the government announced that Nobita's birthday will be a public holiday from then on. The drawback of such popularity is that poor Nobita never gets a moment of peace or privacy, so eventually he had to ask Doraemon to get the gadget to change everything back to the way things were.
Some episodes contain little moral lessons about friendship, kindness, the environment etc.
Characterization is fine, as the lightness of the show doesn't call for for deep, complex, nor enigmatic characters. The anime is also entirely wholesome. The only violence in the show usually involve a big fat bully called Giant whacking Nobita on the head. Doraemon himself is highly amiable and I am sure most children would want to have a friend like him. It's a pity that Doraemon was never released in he US because the anime does seem to have a cross-generation appeal, as wherever Doraemon is shown it becomes popular.