Certainly one of the biggest changes in Victor's personality is a return to humbleness by understanding the complexity of life but, most importantly, the complexity of humanity. Victor took life for granted. He assumed that life was yet another scientific method that anyone could re-create the way one does any other scientific investigation. Yet, he never fathomed the consequences of trying to meddle with what is already universally accepted and sacred by all standards.
Once, Victor was a creature of hungry ambition. He was pompous and arrogant in thinking that he was untouchable and invictus. He went with his whims and ate up every literature available on the topics of chemistry, alchemy, biology, and life itself to satisfy his arrogance. Yet, in the end of the story we see that his creation was his death sentence. He lost the love of his life, his best friend, his credibility, his happiness, his passion, and most importantly, his sanity. In the end his final words were: I am the wretch.
Just imagine his feelings at that point in his life. He, once a self made godlike figure, bringing himself to that low spot. It must have been a horrid moment for him, and a huge reality check.