Paul Brooker's Non-Democratic Regimes: Theory, Government and Politics reads like an extended literature review of non-democratic regimes. It is an extremely useful introduction to the field and literature on totalitarian and authoritarian governments. Brooker clearly outlines the major types of authoritarian regime (party, military, and personalist), as well as "subspecies" within each. He then discusses various issues arising with such regimes, including gaining power, maintaining control, and transitions to democracy. Within each chapter, he is careful to differentiate between the various types of regimes and point out similarities. As far as I can tell, Brooker never proposes any new theory or framework in this book, but that's just as well as his book fills a gap in the literature. Overall, you can't do much better if you want an overview of non-democratic regimes.