For anyone that judges a book by the stars on the article that introduces it, pay no attention to the paltry 3 stars. That was due just to a mixup on when the article was released and when the electronic versions actually became available. This is a 5-Star MUST READ book! I did an indepth review on Grant's first edition on the subject and this second edition update is frosting on the cake.
The ebook/PDF is nice but if you don't have this one on a physical shelf, you're missing out.
Heh... and, no... I'm not a RedGate employee and I'm not Grant's long lost cousin! 😛 It's just a great book and it'll make you a better DBA or better SQL Developer.