It seems to be written for the parent to read to the child; after all, a book introducing the letter "A" is not for a child already reading. So, we're looking at a child between the ages of 3 and 7. And this book as one of the first looks at the letter "A".
But the letter sounds used are "a" as in "ant", "angry", "across" and "aaaarrrgh".
The problem with this, is that most phonics methods introduce only one "A" sound at a time (usually the short a sound, as in "ant".) To introduce all these sounds at once for just one letter can be confusing to a child.
Also, there are only 28 words in this book, but several of them will be unfamiliar to the average 3, 4 or 5 year old. Such as "advance" (as in what an army does), apricot, angleworm, acorn and Arizona.
I think this book could be confusing to some children, and isn't worth much in terms of teaching a child beginning phonics. This is definitely not my favorite Berenstains' book.