As a classics major in college, I have been regularly referred to the Roman section of this work to gain increased general knowledge over later classical antiquity. After thoroughly reading and rereading many sections, I can scarcely say I've gleaned anything close to that.
The "chapters" read more like non-peer reviewed articles that are virtually impossible to understand for the casual reader, and very difficult for classics students. They constantly diverge from their central theses, lack chronological sequence both within themselves and in relation to other chapters, use highly colloquial terms and accentuate seemingly arbitrary themes throughout history while ignoring others.
Cases in point: Marius' name is mentioned about 3 times, and never in regards to his own exploits. Cinna is missing entirely as far as I can tell. The Catilinarian conspiracy receives about half a paragraph (even though Sallust devoted a book to it and Cicero couldn't shut up about his own involvement), as do the Gracchi brothers, and Cato the Elder, but we receive heaps of names about obscure groups in the Italian peninsula during Rome's expansion, whose importance as individual tribes is obfuscated by varying levels of information which seem to lead nowhere, while their individual legacies are absent. The exact identities of "Roman", "Etruscan", "Latin", and "Italian" are anyone's guess. When the political division between the "populares" and "optimati" are introduced, the latter term is left undefined. Very, very shoddy.
I have not read the Greek section yet and refrain from commenting upon it.
The Roman section of this text, I think, is a disgrace to the Oxford University Press. If you want to learn about classical history, I suggest you read an array of entries from the Oxford Classical Dictionary, a thick but condensed reference work that cuts through much of the subjective interpretation of events to the meat of the matter, giving you the "who's who" and "what's what" in concise entries.