Pros:
Children are more familiar with classical structure than with any other types so they know what to expect and can follow it easily.
They might be able to predict what comes next in a story which get them more involved.
Cons:
A not classical structure may contribute to their cognitive and emotional development better. If the events are told in nonlinear way, they have to grasp a more complex story and if for example, a story is told from a different points of view, they have to able to imagine themselves into the place of different characters.