This is one of my 10 month old's very favorite books. When he goes to his little bookshelf, this is the book he invariably pulls down and flips though. When I read it to him, he is totally riveted. When he flips through it by himself, I see him touching the ladybugs (since they're 3 dimensional) and exploring the holes on the left.
This book is brilliant and works on many levels. It's very melodic (great rhyming verses w/out being too sing-song-y). Example: "Ten little ladybugs, sitting on a vine. Along came a caterpiller, then there were..." turn the page and you get "nine little ladybugs...."
Plus, you've got each number on the page represented 4 ways -- on the right, you see how many ladybugs remain (i.e., 10 of them). On the left, you've got the number displayed ("10"), plus the holes add up to the same number, and then the verse at the bottom has the number written out ("ten little ladybugs...")
All the characters throughout the book (the caterpillar, the grasshopper, the turtle, etc.) show up at the end so you it's not like they come & go and are forgotten, and each page is beautifully illustrated. The book is also very well put together and I don't fear that the ladybugs are going to come off when my son grabs them. This book is very well used in our house and it's still holding up incredibly well. We highly recommend it!