Review and Ratings:
Concept/Innovative : 0.7 - This is a virtual instrument app. User can play pads using this app. User can create custom pads too.
Usability: 0.6 - For beginners its some what hard to understand functionality. Tutorial could have appeared as soon as app launches.
Functionality/Correctness : 0.8 - Found few issues but can be ignored.
User Interface : 0.6 - User interface is good but can be improved.
Performance : 0.7 - Overall performance of app is satisfactory.