You, as an adult, will not feel like this is worth the $1.99 you paid for it. But remember, it is for your 4-year-old.
There is only one game: collecting letters as you fly through the sky. You can play as any of the four main characters. There is a single mode of interaction (tilting the device to steer left and right) that might leave some children bored after a few minutes. That also means that your child has to be holding the phone/iPad and moving it around which will probably make a lot of people nervous. The replay value is limited since it very repetitive—which is, albeit, good for learning—and the only novelty with each play is that you are collecting letters for a different word.
On the plus side, the graphics and sound quality are top notch. And if your child is at just the right stage of physical coordination, ability to pay attention and interest in reading, then they will have fun with it.
AD&P about SUPER WHY Alpha Boost!