I like it so far. He's dealing with all different variations, starting wih the Exchange and there is a mixture between his own games and important ones. What was interesting for me is that he uses a lot of space to Steinitz lines (old and new ones), not a lot on the absolute main lines in the Spanish. I believe this is vergin ground for chess books? Or at least, these lines are not that popular anymore. 

I really like the stories and his commentary, too. 

I have the e-Version, and for like 10€, it's really nice!