Several months ago, I read J. J. Gibson's 'An Ecological Approach to Visual Perception', which was a relevant text to understand before reading this book. It acts as a precursor, laying the foundations of perceptual geometry and physics, to the knowledge in 'The Dynamics of Architectural Form'. So, if you are interested in reading this book, I would say J. J. Gibson's text is a necessary (or at the very least, incredibly useful) text to understand (even though it was actually published after Arnheim's book, I believe it should be read first).
The book builds on the existing knowledge on perception within an environment, adding levels of complexity more relevant to the field of architecture. Not only is it packed full of examples of historical pieces of architecture doing things right or wrong, but Arnheim has a poetical tone to parts of his writing, which expresses his awe towards some buildings; it really is a beautiful book to read. His analogies, used to explain fairly complex architectural and geometric theories, are unparallelled.