Google is now pushing out a new version of Hangouts, the one that we reported that would be capable of sending and receiving SMS with. The update to Hangouts makes it equal to the one that ships with the Nexus 5 smartphone, which is the default SMS app on the device.
Once you've received the updated Hangouts app, you'll be asked to enable SMS support - something you can decline - but if you turn it on, you'll do all of your text messaging through Hangouts from now on. This is great for those who don't already use a third-party SMS client, as it keeps all of your messaging in one place, up in the cloud, and on your device. The update is going out gradually, but here in Australia, I'm not enjoying the new app yet unfortunately.