I read it once a year. It changed how i think about everything. My career is based on this book. My interaction with people and groups of people is based on this book.
Yeah, it's a starting point, but still the best one with the most clearest thoughts. Every other System Thinking Book is more specialiced to one domain and seem to drive additional agendas.
I can recommend everything else she has written. I go back to "Thinking in Systems" once a year and analyze my life, my projects again with her framework. There is always something new to discover.
I read it once a year. It changed how i think about everything. My career is based on this book. My interaction with people and groups of people is based on this book.