Epic. Bought the hardback version 2nd hand because I wanted nice big versions of the maps on the endpapers, and also realised I'd be spending much of my time flicking to the extensive glossary at the back and the character list at the front. Having suffered from a modern education this was my first proper introduction to Roman history. I really appreciate the depth of McCullogh's research for this series, and liked her illustrations of the main players through the book.
I tried loaning it to my mother, but she really struggled with the number of characters, particularly the number of names to remember, and I think she eventually gave it up.