Apple currently has no support for demo apps in the app store, but will allow free and paid versions of the same app. The free versions of Intervallogic for either OS have only two exercises: Triads and Intervals. And these do not include the user selectable levels that are available in the full versions. The audio quality and general operation are the same as the full versions. Use of headphones, or other high quality audio playback is highly recommended. As with any headphone audio, be careful to check the initial output levels.