In many ways this is the climax of John’s Gospel. It is the most spectacular of Jesus’ signs, and it is the impetus for growing opposition to Jesus on the part of the religious leaders.
Like other narratives in John’s Gospel it provides the opportunity for dialogues (between Jesus and Mary and especially between Jesus and Martha). The dialogues provide the opportunity for Jesus to tutor the sisters in the deeper realities of faith.
It seems that Martha, especially, represents a traditional belief in the resurrection of the dead as a promise for the Last Day. Jesus does not deny this future aspect of resurrection, but even more he insists that he is the resurrection and the life, right in the present.
In some ways Jesus seems very human in this story, but in other ways his reaction is strange (notice how he delays going to comfort the sisters). Some scholars have thought that in John’s Gospel Jesus is more nearly superhuman than human, and this is one of those stories that invites us to think about that question.