And how!  First, the whole idea of playing God is very controversial.  In fact, when she first wrote the novel, her husband, Percy Shelley, burned it because it was so horrifying a story--much less written by a female!  Even so, when she rewrote it from memory, most people still considered Percy to have been the author due to its dark and sinister nature.  Dead things coming back to life, creating life and controlling who dies, etc.  Manipulating science to do the will of man (similar to the controversies today of selecting certain genes for your future baby so he/she will have blue eyes, higher intelligence, no freckles and also the whole cloning thing).  There is also the idea that if and when man plays in the world of God, man loses control since he is without the necessary information to make it work.  For instance, Victor doesn't think beyond his own hubris and fame while he works on his creature.  He never considers where or how it will live, that it will be an outcast, that it will be stronger and smarter (despite the fact that he creates it to be superhuman, 8 feet tall, and chooses the brain of an amazingly smart recently passed person to create his man), and that it will eventually turn on him and seek revenge.