This app was very thoughtfully designed, it’s a great music player interface (and not just a generic media player like VLC). It’s very easy to add all your music and then you’re good to go (I have like 30GB so I just plugged into my laptop’s usb and copied it all over, but you can also use WiFi or share files over from other apps on your phone). One tip is that the app’s music library is included in iCloud backups, so if you want this then great, but if you’re like me and don’t want all that copied over the Internet and maxing out your iCloud limit, go into your iCloud settings, into Backup, and you can toggle off backing up of Doppler (like any app). The app is free to try for a week, personally I really like the one-time purchase vs having subscription fees.The bad news: I submitted both a feature request and bug report (“Import from Cloud Services” black screens for me, so doesn’t work at all) and got no response, so this app may be abandoned, which would be too bad. It’s still worth $9 to me but does lack some features (lyrics, album info, visualizations). And after mass-updating my song library’s metadata offline, the easiest way I could figure out to refresh it in Doppler was to delete the app, reinstall and start fresh.