Google has added quite a few new features to Hangouts since the original release. Most notable here was the SMS and MMS integration which arrived with v2.0 a few months earlier. But despite new features, Google still doesn't offer one piece that many have been asking for -- a quality widget. Well, thanks to a third party, there is now a widget available.
The app/widget is called Hangouts Widget and it is available by way of the Play Store, and also in APK form on the xda-developers forums. The widget comes by way of xda member RSenG2x who has released the app with support for Android 4.3 and 4.4. Hangouts Widget is currently sitting at v1.0 and will show incoming messages (to include text) without the need to fully open the regular Hangouts app.
The widget is resizable and should serve to make replies a bit quicker. Or at the very least, with a few less taps. There is the obvious in that you must have Hangouts installed and up to date before the widget will work. There was also mention of the app only being able to show new Hangouts.
"Because of limitations to the Android system, only new Hangouts will be shown"
Otherwise, while currently sitting at version 1.0, it appears this is still somewhat of a work in progress. Based on comments from the xda-developers thread the setup seems usable, just not quite as feature rich as some would hope. Basically, there weren't many complaints in terms of how the app functions, but some are already looking for more such as the ability to run this on the lockscreen.