We got this from the library (twice) since he recognized the second time and wanted it again. It is the first book that he "read"- at least could repeat the letters after I read them- at about 22 months. I'm thinking of getting this one and others in the series for our library since it was such a hit and really made him seem proud when he got the letters right.
It's a pretty cute little book that you can sing along to. My daughter loves books that we sing to so I found this series accidentally and bought a bunch of them. I think The Itsy Bitsy Spider is her favorite but this one is cute too.