My 4-month-old daughter LOVES Sandra Boynton books. We have ten of them and they are her favorites. She loves the simple stories and the bright, vibrant pictures. I point to the words and the pictures as we go through them & she giggles almost non-stop. She even tries to help me turn the pages. (Of course, she also has tried to eat the books, but she's only four months old.)
There seems to be a lot of discussion regarding the "ugly birds." As an education professional, I think it is important not to under-estimate the intelligence of children. Many will take the phrase at face-value and see it for what it is, a silly statement that sounds funny and "tickles" when you read it.