Google recently launched Hangouts for iOS and Android as a replacement for Google Talk and several other messaging projects. To keep it short: Except for the group video chat feature, the app is more or less like every other mainstream messaging app.

Google Hangouts App
Standard messaging app with simple and clean interface
Hangouts has a simple and clean interface. If you know how to use your texting app or are familar with Whatsapp, Line, Skype, etc., the UI will be straightforward for you. The new Hangout screen with the large photos of your favorite contacts is nice.
In addition to text, so far users can only exchange photos. However, it is quite likely that other digital contents like locations, voice messages, video, contacts, etc. will be available in the future (if Hangouts wants to gain a minimal market share only, they will need these features…most of their major competitors have them).
Group chats with video feature
Like most messaging apps nowadays Hangouts offers group chats. However, unlike other messaging apps Hangouts also features video group chats where you can chat with up to 10 friends.
The current versions for iPhone and Android have several bugs and performance issues (e.g. video chat crashes the app, and also the audio seems delayed quite often). Overall, except for the video chat maybe, we don’t see a need to use Hangouts. There are too many other similar, but currently better performing messaging apps out there.