I have used several of these books now since January. The 4 year old that used this book (previous edition, but I scanned through the updates at Sam's Club and there don't appear to be any big changes) has shown significant progress. She started without being able to write any letters or numbers and without being able to identify any written numbers. Within the last 5 months and fully completing this book, and some supplementary reading lessons she is able to recognize and write numbers 1-14 fluently as well as recognize most letters although she struggles with the sounds that many of them make. She grew bored of all the coloring in the book and started scribbling instead of coloring on some of the pages (which I allowed as long as she scribbled or circled only the ones starting with the correct letter).
The one thing that is frustrating is that there aren't many reading lessons built into the workbook. However the last few pages assumes that the child can read. In addition, the first grade book goes to fast with the assumption of reading for the beginning reader. There needs to be a smoother bridge for this series. Also the first grade book (both this addition and the previous edition) have some sheets which have confused both children with the subtraction problems as they draw out objects for the numbers on both side of the subtraction sign. Those should really be revamped (for the one that already new subtraction I told her to ignore the pictures and just look at the problems and for the one just learning subtraction I crossed out all of the second set of pictures and had her cross out the number of pictures that we were subtracting using the numbers in the problem).
For the struggling first grader in first grade the first grade book worksheets are either too easy or really hard. The first grade book doesn't have enough word problems (she does word problems that include multiplication and division at school and this doesn't stand up to it). However, lessons like the clock lessons made her have a great day while other students in her class were struggling with it. She (and her grandmother when she visited) really struggled with parts of it like the synonym unit and which one doesn't belong because they aren't always straight-forward for some
people -- like what is a synonym for "dimes"? Coins, change, money, currency...how do you teach how to come up
with stuff like that to someone else? Or that you can list a type of store for a synonym to it (not 100% true, but what the book expects).
Once you get past the super-fast reading primer the first grade book looks similar to the second grade book (with more reading in a paragraph form for the second grade book).