My son starting learning his letters on a Vtech baby "laptop." By age 18 months he could point out and rapidly recall each letter of the alphabet. I got him this app b/c I wanted him to further cement that knowledge base and be further interactive. Now, he just turned 2, and is able to easily finger trace most letters, numbers and shapes. Hes advanced, yes. However his 4 yr old sister has similar abilities by using these 2 tools. They are ahead of the game and seem to love playing the apps.
Ps, Im not some rep for the app. Honestly! If you go on Amazon you can find iPad , the original, for about $100 dollars. Its not update able past iOS5.1, but I havent ran into any snags with them and my kids love these iPads. I now get mine back! Sweet Heaven!