If you love to play the blues, I strongly recommend it. It has different sections from Pre-war and post-war blues to Delta, Chicago and Texas blues. It even has post-modern blues. It even has text in it that gives context to what you're learning.
It's not teaching specific songs, but what it does teach can be used in nearly every single blues song - it even has a list at the back to show you which songs.
I would give a 5 star, but I've not used it to its full potential yet.