Thank you so much for the detailed feedback and for testing on a Galaxy S5! That's really valuable. I will consider all your points.

About the browser section: The login issues you saw on Steemit and SteemWorld are not related to Steem Keychain itself. I only provide the browser, the dApps control their own login flow. Steemit does not support Steem Keychain login on mobile. For SteemWorld, the authentication actually works, but the dialog stays open as if you didn't authenticate. You just need to close the dialog and you will see that you are actually connected. You can see it in the demo video at this timestamp:

Any dApp that integrates the Steem Keychain API (like SteemPro) will work perfectly, the dApp just needs to support Steem Keychain on their mobile UI.

Really glad the app runs smoothly even on your older device. I will let you know when the new update is ready. Thank you!