Claudius the God is the sequel to the legendary "I, Claudius". Though not quite as powerful as its predecessor, the book continues the story of Claudius after his ascension to the throne.
The book points out the many pitfalls of ruling a state; Claudius, sadly, is as much at the mercy of his wife as the Emperor Augustus was his -- a blind spot that nearly costs Claudius his throne. The advice Claudius receives from his friend Herod Agrippa in the beginning of the book -- to "trust no one", is indeed good advice.
As a character, Herod Agrippa steals the book -- the book's first seventy or so pages deal with his story, which form a very amusing and interesting digression -- and shows how Herod Agrippa's influence in Rome is instrumental in bringing the Senate around to recognizing Claudius.
Claudius introduces legal reforms; converts the harbor at Ostia into an all-season port to help secure Rome's food supply, conquers Britain, and revives the Roman religion. The book is a wealth of historical detail and interesting anecdotes.
The book is also engaging and entertaining; although one soon sees that the job of Emperor is no fun indeed -- Claudius has as much cause for paranoia as any of his predecessors.
The book is a must read for anyone who reads "I, Claudius", and is a very good work of literature that brings the Roman age to life.