I've only just gotten around to reading my guides from Greece which I picked up in 2014, mostly because I'm contemplating a student trip in 2020, so I wanted to remind myself what I could see.
The starting place with this book is that this is a guide to the Museums of Corinth, Isthmia and Sicyon. There is useful discussion of the sites, their layouts and such, but the focus is on the Museums' collections. It includes good photography of many most notable holdings and a good overview of these classical sites. The photos are getting a bit dated, but that is about the only objection that I have.