First of all, this is NOT, as the title claims, a cheat sheet to The Four Steps of the Epiphany.
Right in the book, on page 21, the authors state that this book focuses on the first step only (Customer Discovery). And I quote: "Future books will attempt to tackle other portions of the Customer Development process - believe us when we say that Customer Discovery is more than enough to 'bite off' at one time."
I am docking the book one star for this. The authors should know better.
Okay, now for the real question - Is this book worth getting, or should you just get Blank's original?
Get them both. Read Blank's first, then read this one and use it to update the notes you took from Blank's book. They work well together but I would not just get this one, as you only get a small piece of the whole picture (per the authors' own admission).
It's worth $30 if you actually use it, but don't assume it's a shortcut to Blank's book. It's only 1/4 of a shortcut.