e10s release is going as per Mozilla plan. Initial phase of e10s release has been already out to 1% of the eligible users with Firefox 48 release and is a success, now the browser vendor is looking to up the e10s activation to 10% from 1% by shipping Firefox 48.0.1, eligible users here should not be using add-ons, touchscreen and accessibility tools. If everything goes perfectly, Mozilla may ship period release today itself via a GoFaster update of the e10srollout add-on and Hello.

Firefox 48.0.1

FYI, you can still enable multi-process Firefox in Firefox 48 even though its disabled by default to you.

READ this: Check Firefox 48 has E10s Enabled/Disabled, if disabled here is how to Enable

By following the instructions mentioned in the above link you can able to use multi-process Firefox, so far no issues have been reported by doing like this and you should note it also depends on extensions you install for e10s activated Firefox browser to behave stable.

You can check the release notes here, when the version officially releases.