Hadley is a true critic. If he doesn't have something nice to say, he says it anyway. Read his reviews every month in Downbeat for proof of that. He has very eclectic tastes and does not suffer singers who cannot sing or express the song or writers who cannot write. He points out the good and bad of performance and production. I am tired of critics being afraid to say something is no good or at least point out faults in a recording. Sometimes the emperor has no clothes and the critic needs to tell us that. I do not see any bias in favor or against any type of blues or any era of blues in his book or in his Downbeat columns, only criticism of failings that need to be pointed out. If you do prefer a certain era or style (we all have our own preferences and biases) this book will point you in the right direction for blues you will appreciate.