I'm writing an iOS app that requires backend access. Is it a bad idea to have users sign in with their Google Account? The app doesn't need access to user's Google data, except that the backend is hosted in Google App Engine.
Personally, I don't like anything that makes me sign in, with any login. If you're asking this question, you likely realize that, too. I suppose another question you should ask is whether you really NEED that login. If it is absolutely required for your app, and the app provides enough value to the user to overcome the bother of signing in, then okay. However, if there are other apps that fulfill the same purpose as yours without requiring signing in, I personally would just delete yours and go download another option. Any login at all is going to be a hinder to adoption.