From the well known Wee Sing music based learning products, Wee Sing & Learn ABC app is available for free download for a limited time. Normally, this app is $2.99. This app is produced by iStoryTime.
This app does a good job of creating an interactive beginning ABC learning app. You have the ABC song, a play along with the song, interactive ABC animal and musical instruments flashcards, and an explore the letter names. The app is pretty interactive and engaging. However, it is not worth a paid app price of $2.99. There are apps that are far cheaper or free that accomplish the same things although not necessarily all in the same app.
Recommended for ages 18 mos to 4 years. Grab this while it is free!