I used this book in my Comparative Politics class in order to frame a discussion on the state, theories of the state, the process of state formation and the components and the subunits of the state. The book is really informative in terms of basic definitions and an extensive overview of theoretical approaches. So if you want some referential insight on the basic concepts regarding the state and its capacity, I think this is a good book to start with. The only critique would be the Western bias it holds because of the cases it relies on and the lack of alternative cases and theoretical approaches from the non-Western world, but that's kind of a common problem in all of Held's writing.
To me, this is a general reference work on political theory in terms of state power. Frankly, it is a tad dry but useful. It is broadly based with reference to many types of political theory explored in other works by the author. Application to modes of state power and statehood change with theories. I always felt I would get back to the author with some of his other works but that has not happened.