Make video calls of up to 10 people at the same time.
It is possible to use Hangouts on computers, in addition to cell phones.
It is possible to share your current location.
It has a series of emoticons and GIF animations to share with your friends.
It is possible to send voice messages.
It is not possible to place your profile as Invisible, compared to Google Talk.
It is only for Android devices and also with iOS. For example, WhatsApp is in many operating systems. The fact that the Hangouts system is based on a closed system, can play against, due to the low ease of expansion.
You can not send multimedia files at the moment, and this plays very against you, because Telegram, to give an example, allows you to send files of up to 1GB.
It is not possible to know if the message was received by the recipient, or if it even came from our cell phone, in comparison with the other more well-known services.
most meetings and trips of professional life are unnecessary, could be resolved perfectly with a medium such as a videoconference via Hangout. All this without mentioning that many of the meetings tend to be somewhat unproductive, I, at least, avoided them as much as possible.
The problem of this is purely cultural, many clients will not feel comfortable because they simply have not tried it yet, but others, although few, will be open to this possibility, they will even appreciate it once they see its advantages.
Plan it not only with clients but also with suppliers and collaborators, even if you only manage to create this habit with a few, any improvement in productivity is good.