As far as I've tested, I'd say USB output is very good but USB input may not be practical unless you have android device with very low input latency like Galaxy Nexus or Nexus 10. Pls. Let me know if you find Android device which have similar input latency as Galaxy Nexus or Nexus 10.
Sk lee is the official developer of the app which can be found in the Music & Audio category. The most recent update of the tool was launched on Feb 20, 2019 and Practice Player Live Midi +Usb was downloaded by over 5K users. The average score for this application is 3.4 on Google Play.