Grant does not focus on the salacious side of Nero as most other biographers do, although he shows enough of it to allow the reader to understand the corrupt and perverted character of his subject.
Instead, he focuses more on his leadership abilities and what he acquired for the empire, one of which was to free Greece and allow it to become an independent nation again.
Nero is a prime example of why leaders should be elected according to their abilities for the task and not inherit the position. Firstly free election eliminates a lot of murder. When Julius Caesar declared himself emperor he pretty much guaranteed his own assassination. This was true for all the emperors of the first century.
Except for Nero, he committed suicide but only because he knew his death was imminent and he didn't want his body desecrated.
Not that he minded desecrating his own body; what a pervert.
However, what outraged the Roman citizenry was his obsession with the arts. Instead of governing the people, he spent most of his time acting in dramas, singing in operas, writing poetry. According to Grant, this was insufferable to the Romans because it was unfitting for a leader. There were a lot of things Nero did that should have been unfitting for a leader.
And there was the paranoia that naturally comes to someone who murdered his way to the throne. This was probably the final deal breaker, for at least the Roman leaders. They figured they would need to get rid of Nero before he killed all of them off.
This book is not long, so probably not exhaustive. Grant draws mainly on first century writings, such as that of Suetonius, Tacitus and, to a lesser degree, Josephus.
I would suggest reading contemporary writers of Nero first.