He developed a strand of thought known as Negative Theology. In this strand of thought God is described by saying what he is not.
He would say that God has no attributes. Because attributes are either accidental (something that you can change) or essential (something that you must be). Since God cannot change (has no accident attributes) and God cannot be described (has no essential attributes) ergo God has no attributes.
Maimonides early life was easy. Growing up as a Jewish boy in Cordoba. Religious freedom was a given. This ended when a Muslim sect the Almohads took control. They didn't allow the practice of Judaism. The Maimons acted Muslim in public, but practiced their Judaism in secret. They eventually found this too difficult and gradually found their way to Egypt where they could openly practice their faith. He needed to end his studies when his father died and his wealthy brother perished, so he became a physician in order to support his family.
Personally I think Maimonides was picking at straws a bit. How is it so different to say that God is powerful then to say that God is not powerless? Isn't that saying the same thing?
I do think he showed some wisdom in insisting that we not anthropomorphize God. God is SO MUCH greater than people are that to say that God is love so often limits people to how they understand love and that limits God. God should not be limited by our finite understanding of who God is infinitely.
Sources:
Britannica.
The Philosophy book
Chabad.