I always find GarageBand to be an easy-to-pick-up app that can be used to generate fun sonic blurbs in a short amount of time. It has its own limitations, but the lack of complexity contributes to its ease of use.
When I was trying to figure out something on GarageBand I ended up on YouTube looking for tutorials and was astounded to see what people are doing with GarageBand on their phone. They play the DAW itself like an instrument and build songs in realtime. It was very humbling to see.