I use one of these to listen to podcasts and Audible audiobooks. It has physical buttons, so you I can pause tracks and skip by touch, rather than having to take a phone out of my pocket, unlock it and press on a touch screen. With some cheaper MP3 players, if you turn them off, they forget where you got to in an MP3 file. That might be fine for 3 minute tracks, but its a pain for an hour long program.
You get a headphone amp then. This thing is tiny.
No Bluetooth.. :(
You don't have much choice if you want to power up a big headphones ;-) smartphone won't do that good as a standard mp3 player
But cheap androids, in fact most phones, sound awful.