I'm going to forego my preferred Good (what I liked), Bad (arguable weaknesses) and Ugly (unforgivable sins) because I don't really have anything to say in those two negative categories. Instead, let me just talk about who would find the book useful and why.
Group 1: Parents who feel their own math skills are weak.Maybe you never really understood what multiplication means or what fractions are? As long as you start with an open mind and are willing to engage playfully, the activities in the book can help you as you help your kids. It starts with models that are visual explanations of the concepts. Gaskins also breaks learning these concepts into comfortable steps that emphasize patterns and relationships, the real ideas that are behind properly understanding multiplication and fractions (indeed, math generally). The sequence of games in each section starts by building familiarity and then fluency (speed) to solidify all of that work.
Group 2: Parents who worry about their kids struggling with these conceptsAnecdotally, these two areas are the first major stumbling point for students in their math studies. As I noted above for parents themselves, the sequencing in the book will help kids develop a strong foundation, beginning by understanding what multiplication means (and what fractions are). Beyond that, playing the games will make these concepts familiar and, I believe, lead them to recognize examples around them in their daily lives.
Group 3: Families who like to play gamesKids (and parents!) find these games fun. I've been field testing math games for the last 18 months and keep seeing how engaged kids get when playing math games. I have played many, though not all, the games in Multiplication & Fractions and strongly believe the games in the book will be winners with most kids.
Now, let's face it, you might not be thrilled with every game. For example, I wasn't so excited by the idea of playing War variations. However, a lot of other games in the book that are strategically and mathematically rich. Also, truth be told, my kids and students have really enjoyed playing multiplication war!