I know that Mary Beard knows a lot more about Roman history than I do, but I don't think a general history like this shows off her knowledge in the best way. It's simply trying to cover too much in one modest volume, even though she chooses the (somewhat arbitrary) cutoff point of the early third century CE for an ending.

There's a lot that gets covered here - social, political, military, cultural and other forms of history all show up - but too much to make the story coherent so it's more a series of roughly-linked vignettes, rather than an overall history. It might have worked better by having a better focus on a few of the interesting stories she tells (and Beard is a good writer and storyteller) rather than trying to make it into an overarching history.