If your app is in beta or is newly-released, I can give you valuable feedback and report any bugs I encounter. Does your app or game have pleasing a design and color scheme? Is the menu navigation intuitive for users? Are there any missing elements?
Some considerations I have when testing Games: Easy to play?Challenging for target age? Educational, yet fun? Addictive? Engages attention?
Some considerations I have when testing Tools: Easy to use? Efficient set up? Little user-maintenance? Useful and effective?
My phone is the Samsung Galaxy S5 and I can test apps in Google Play and the Amazon Marketplace.