For each letter in this book there is an animal name, an animal sound, an instrument name and an instrument sound. There is so much information that my 2 year old daughter (who we bought it for) is not interested in it at all (prefering the simpler Princess and Dora books). However my 3 year old son loves it and keeps borrowing her Tag Junior just to look at this one book.
Therefore I recommend this to be a book you get when they have grown out of some of the simpler ones. As a music teacher, I find some of the instrument sounds a bit dubious but it's great for what it is and the age group it's intended for..