Daniel Cohen's book is based on an assumption that you know musical notation as far as you would learn it in the first few months of normal piano lessons. Apart from that, he starts at square one.
Daniel Cohen's book includes a CD. Even if you read music 100%, the inclusion of a CD is important. Blues rhythms are only approximated by musical notation, so you need to be able to *hear* them if you are going to play them right.
He starts from ground level - the is no assumption that you already know the chords for a 12-bar blues. Step-by-step exercises quickly get you playing simple but satisfyingly authentic sounding blues patterns.
Then he shows you a number of simple building blocks that can be put together to make your own blues solos. He goes on to cover turnarounds and endings - more blues building blocks.
The way Daniel Cohen presents his material all hangs together - for example he gives a demonstration of how the blues scale of the root note sounds fine when played over the three main chords of a blues tune. As soon as you have heard this and learned the notes of the scale, you will be picking out your own blues solo patterns.
One of the nice aspects is how Daniel Cohen's enthusiasm for the music comes across and how he gets you to avoid hangups that might otherwise inhibit your blues progress.
Obviously, one 24-page book (and its 54-track CD) won't cover everything. But if you work through each of the exercises, it will get you off to a very good start on your way to playing blues piano. And you will be on the way to REALLY playing the blues - not just being able to trot out two or three songs with no further way forward.
"Daniel Bennett Cohen Teaches Blues Piano" gets my wholehearted recommendation, with no reservations at all.