This book takes the conceit of first-person historical narration and lives into it. It is a fictionalized history, ostensibly written by Claudius, historian and emperor, as a frank account of his family history. For the actual history, Graves borrows heavily from (read takes huge chunks of interpretation from) Tacitus, a Roman historian fascinated with the power politics of the emperors. In other words, Graves had a historical source that fictionalized extremely well.

I'm something of a fan of fictional historical works, and this has everything that's needed for a great one. There are humorous digressions, cameos by well known figures, and a well-written first person voice that straddles the line between effectively reproducing the style of a historical work and being open enough to be interesting. There are also some light fantastical elements, prophecies in historical fiction works have a tendency to be true in ways the readers but not the characters will recognize.

Overall, I definitely liked it, though I'll say my interest in Germanicus ran out long before Claudius' did.

P.S. The TV version of this is pretty good too.