Ranked in these QuestionsQuestion Ranking
Pro Free and open source
The code is licensed under GPL (may change in the future) and is available on GitHub.
Pro Multiple front-ends for multiple platforms available
At the moment there is no official Tox client, but a selection of 32 and 64 clients for Windows, OS X, Linux and Android is available.
Pro Privacy focused
Tox uses military grade encryption and works completely peer-to-peer.
Con Early stages of development
Since Tox is relatively new, it has important features missing (like group video) and requires a proper code review before it can be deemed reliable and ready for everyday use.