Create an account, enter a username and password.
Click on the name of your platform, enter your credentials from step 1, and click a checkbox to activate.
Go back to the platform to see my app running.
To update the app, update the GitHub project. "Continuous deploy."
This is as simple as it can be, and if you do it, I will use your service, and more important, if it's reliable and affordable (say $10 per month), I'll recommend it to my readers and users of my software and of course I will use it myself.
Of course it has to be reliable and perform reasonably. Scaling -- not such a big issue. The idea is to have people running their own apps in the cloud, for them, and their friends, or a workgroup in a corporate setting.