Quite readable, but the concepts are deep. Dworkin is a philosopher, and to fully understand his theories of law requires a good bit of work, and a decent understanding of the law and of philosophy.
I enjoyed his style of writing: deep but conversational, academic but accessible. I found myself more and more drawn to his theories the more I studied him. He certainly challenges the status-quo theory of Positivism, which is much needed. Too many accept legal positivism too readily.
If you enjoy philosophical writings that are readable, and enjoy the interaction between law and society, you should read this classic book from one of the world’s most interesting legal philosophers.