Google Sign-In is getting better with moving to an enhanced user experience and higher conversion rates for developers and end users.
Over the last year, we've simplified the user experience by reducing the default amount of information requested from the user and updated the branding.
The new streamlined experience begins with updated sign-in buttons that reflect new Google logo design, and furthermore, it now works for all users, not just those with a G+ profile. The new sign-in also comes with redesigned consent screen that show all the information that will be provided to the app (name, email, and profile photo) inline, and is available on Android and the web, with "iOS coming soon."
Furthermore, Google+ Sign-In is now moved to the new model Google Sign-In.
Developers who continue to use Google+ Sign-In will see some changes in behavior such as: "New users going through older sign-in flow will no longer be asked to share social graph data with your app."
In upcoming SDKs, "Google+ branded assets will be replaced with new Google branding. With that, if an app still uses default button, a new look Google Sign-In will take over," writes google.
And after January 2017, Plus People or Games Players APIs may begin returning empty results, as well as the Plus People API is deprecating now.
For applications needs social information and more extensive profile data, developers can use new contacts-based People API, which provides a rich set of users' connections.
Devs can also use Firebase Invites, to enhance the distribution of their app through the social graphs of your app's userbase. On Android, "rich cloud and device-based Contacts data from the Contacts Provider" will be available too.
For making change to your app, "use latest libraries with default sign-in configuration, or replace "https://www.googleapis.com/auth/plus.login" scope with "profile" and update branding of the Google Sign-in button (your existing users will not be asked to sign-in again)," google explained.
Finally, Google also overhauled Identity/authentication APIs, which now simplify implementation on both the client and server.