Most people were skeptical when Google replaced Google Talk with Hangouts, but to my surprise, it was an easy and pleasant transition. It has basically consolidated my conversations into one location. I can see all SMS, MMS, and Google Talk conversations in one place.
The only thing missing to this already great application was a widget. No, Google hasn't updated Hangouts to include a widget, but we can now have one thanks to Android dev RSen—and it's extremely useful.
All you need is a device running Android 4.3 or above and Google Hangouts installed. If you already have those two things, then download and install Hangouts Widget from Google Play. After installed, go to your widgets, locate Hangouts, and place it on a home screen.
Although in its infancy, the widget does its job well. It's fully re-sizable and the only downside, if you can call it that, is only new hangouts will appear after applying the widget, so don't expect your history to be displayed right away. The widget is new, so the developer has no issues getting back to you with your inquiries or feedback.
Enjoy getting notifications from your celebrity girlfriends, and comment or message with any questions or issues. To see how this works on other Android devices, check out Nelson's guide on using Hangouts Widget on Samsung Galaxy Note 3 softModder.