Actually, there are a great number of art historians who see this "extraordinary cycle" as being by a follower of Giotto and not by Giotto himself.
Above we have a scene from the St. Francis cycle at Assisi (by an imitator of Giotto), Giotto's Flight into Egypt from the Arena Chapel in Padua (certifiably by Giotto), and then the same subject by another copier of Giotto in the lower church at Assisi.
Just look at the composition: Giotto has no distracting, unnecessary forms in cities, architecture, extra trees or anything. The way he has arranged the forms are monumental and wonderfully simplified: note that huge mountain making Mary seem taller and grander and not bent over. The forms are more gently shaded and rounded, and the figures feel heavier and have more mass. The landscape is more terrifying in the real Giotto, and Joseph, old as he is, looks very humanly at the younger, more spry servant. Also, look at the babies: which Jesus seems more alive? One looks like he was stolen from a creche.
The church of Assisi is still a splendid church, on two levels, and I'm thrilled they are restoring it so thoroughly. I just take issue with the Italians who always claim that Giotto painted several fresco cycles there despite the visual evidence that the style is very different and not up to Giotto's standards.