I like these little guides - I keep buying them, because in places like western Crete, Rhodes and on Kefalonia they have been very good for planning and walking alike. The problem, at least for me, with the Corfu one is that the island is rather strung out, geographically, and public transport is (at least in late season, when I went) not very frequent. That means that I was only able to do a single walk, plus a few bits from other walks. As I was based in Acharavi on the N coast not many featured walks were accessible from my base...
I think this would be true for many people stuck with public transport, unless you are based in the Nissaki area; four or five walks are based in this area. All the other walks have starting parts pretty far apart; as long as you have your own transport, you're fine, as from my experiences elsewhere these walks are well chosen and properly explained.
So was I really disappointed? Not at all. Being based at Acharavi gives you access to a host of walks, waymarked with little blue marks, and also to the fantastic Corfu Trail. We had a wonderful time, and walked our socks off!
So my four stars are based on a single walk from this book, plus eagerly browsing (before I left) all the others - many of them look really good.