I have no issues with my mother in law as well. She respects our private life and does not really interfere into our lives. Although she has our house keys, she never come over without telling us in advance. She typically only comes over if we are away on long vacation and requested her help to clear our mailbox.
She is a good cook and makes and effort to cook delicious food when we visit her every week.
But despite all that, I dont't think I will want to stay with her because she is very clean and neat and I'm not (hehe). If I stay with her, I will feel the pressure to "clean up" or she will always have the urge to clean up after me. And I dont't think either way is good.