Well, I have to say, I have never seen my children spend so long studying and enjoying a book in your life! I have subsequently, over a period of time, purchased many books in the series from The Book Depository (which has free shipping worldwide, no matter the size of your order!). They love the books so much they are even enjoying the "Fairyland" book hehe.
There is a huge number of titles in the series, each one as good as the last. The 2 images below show just 2 of the books (I just ordered the Monster book, can't wait for it to arrive).
How the books work is that on each page there is a large picture, along with a specific number of 'things' to find in that picture. So even if your child can't read yet, they can still use these books without your help. I just love these books, because they really get their minds thinking, while being fun at the same time.
So, I really can't recommend these books highly enough for either boys or girls, of any age. Plus they are so affordable at around $12 each with free shipping if you get them from The Book Depository.
Disclaimer: This is a book review conducted by myself simply because we love the series!