Haha not really, the book is written like a diary of Tiberius (same with the Augustus one), just really first hand thoughts of him at all times (not an encompassing regular novel or bio like other historical fiction). Bit of a clever psychological study, and really is amazing how it depicts his intellect and morals, and his cronic melancholy.
Yeah the second part is about his retirement alot, but no it doesnt focus much on depicting his carnal activities (hardly at all), even if he ponders about his desires (homoerotic ones included), and briefly about his lovers. He had a slight special taste for German boys
It focused more on his Rhodes resort then Capri, which was just a bit at the end. And btw, Sejanus is awesome hehe. And also the noble Senators who decreed that we cant execute Sejanus little daughter because she is a virgin (it would be immoral!), so she has to be raped before she is killed