We bought this guide as it seems to be the only walking guide to Kefalonia.
It's less use than the standard Sunflower walking guides, as it intersperses the walks with restaurant reviews and recipes. We didn't really find this much use, as we don't really eat much on our days out, and in the evenings we had our meals in the town where we were based. We did vist (and enjoyed) three of the restuarants listed. We also attempted most of the walks, sometimes adapting them. They're mainly short and undemanding, but as it was still pretty hot when we were there (late September) this was fine.
I'd prefer a proper walking guide, and if I want recipes or restaurant reviews I'll find them elsewhere. There must be plenty more good walks in Kefalonia that deserve to be mapped and publicised. Talking of maps, the single-page island map in this book is too small to be any use, and the walk maps are quite limited.
However, it has its uses and it's a neat little book that fits easily into a pocket or bag. Until something better comes along, it's probably worth having.