I’ve been using it to listen to actual MP3s of the music I have. I can’t find any decent MP3 player on iOS (incredibly ironic given the iPod was one of the 3 devices the iPhone was supposed to be when Steve Jobs first introduced it) and VLC is pretty good.
I’m using VLC because it’s the only one that I know that can play opus. I chose the latter for lossy encoding because I have a few albums that are gapless and it’s hackish to get mp3 to support those (other than single mp3 file and cue file).