I found this article which seemed relevant.
I’ve included this part because I think it is interesting that the app for Adele is a photo of her. It really stands out from the app designs I’ve seen so far as none of them use photos.
I’ve included this part because I think it is a clever design to use the shape of a stamp. It is a simple design using only a few colours but it still stands out and is recognisable.
All of the above are from: