I first read this quite some time ago, but recently re-read it. The edition I have is translated by Robert Graves, revised and updated by JB Rives (a Penguin Classic).
The book is a series of small biographies of the first twelve rulers of late Republic and then Imperial Rome, starting with the dictator for life (but not emperor) Julius Caesar, and continuing through to Domitian.
As you might expect, Caesar, Augustus and Tiberius have lengthy biographies and Galba, Otho, Vitellius and Titus rather shorter (Galba, Otho and Vitellius were all short-lived emperors in 69AD and Titus only reigned two years). It’s a shame and a surprise that Vespasian in particular, who was a good emperor reigning a decade or so, gets a relatively short biography.
The biographies have a slightly odd approach. Whilst they tend to begin with early life and end up with death, the middle parts are ordered according to topics rather than chronology. An emperor’s fiscal approach may be followed by his moral virtues, then his vices, for example. It’s not awkward or clunky, just unusual compared to modern day biographies, which tend to be dictated by the order in which things occurred.
Suetonius is perhaps the single most easy-to-read classical history I’ve encountered (perhaps Livy is close). I read on a forum that some see him as a tabloid historian, which is a pithy summary of his style and the veracity of his offering.
With rare exceptions (Thucydides, Polybius) classical historians were not fixated on accuracy as we hope modern ones are. Suetonius is a bit of a gossip, relaying anecdotes (sometimes mentioning he thinks they’re unlikely to be true) along with facts. However, that does not prevent him painting vivid pictures of the imperial lives, and giving us an indication of how they were seen shortly after Domitian’s downfall.
There really isn’t much I dislike about it, with the exception that endnotes rather than footnotes are used.
Twelve Caesars is a most enjoyable book that’s very easy to read both in terms of the writing style, and that practically no previous knowledge of the era is necessary.