I've had the unit for about a week, invested in a 256GB microSD card. This unit is an audio specific version of a now almost universal technological template - a specialized computer running in this case Android 12. It has Bluetooth and WiFi. I didn't expect a full blown operating system device. If it had SIM capacity it would be also a smart phone. Android 12 takes up about 12GB of the 32GB internal storage. I wasn't too happy about that, but for the functional tradeoff and SD card capacity it's no big deal. The sound is at least as good as my hearing. It's quality is clear. One can have the audio signal pumped directly to output or routed through a number of optional enhancements such as Equalizer, Volume Leveler, a summary "Clear Audio", and a couple of geeky adjustments that may only be apparent if using extreme hifi files. For my 320Kb Mp3s makes no difference. I assume more enhancements means more power usage. Nonetheless, battery life is hardly the 30hr. advertised, but plenty long enough for my usages - 10hr. or so. Navigation has a slight learning threshhold, but once mastered powerful. It takes a bit of time to boot, and rebuild the database, which for 100+GB libraries can take some seconds. All in all I'm very happy with the credit card sized machine. Physically it's solidly built, "heavy" in a good sense. Convenient as hell to carry in a pocket.