This is based on NaCL. NaCL is an extremely great library that we virtually never recommend because it is very difficult to integrate into most people's dev environments.

Libraries like NaCL, Keyczar, and Cryptlib work by removing all the design choices from cryptography. You don't pick the key sizes, you don't pick the algorithms, you don't even pick what kind of keys you exchange. They implement a whole cryptosystem, as if for some new unreleased version of PGP, subtract the file format, and present it as an API. They're great. They are literally the only way you should be deploying cryptography in your applications.

I think this is a great development, but I am not qualified to say. This sits in a weird place in between a language binding for NaCL and a fork of NaCL. As a bindings package it's an overachiever; as a fork, it seems to have made extraordinarily conservative changes.

You'd really like a real crypto dev --- Matthew Green, Colin Percival, DJB (NaCL's primary author; @hashbreaker on Twitter), Steve Weis, Trevor Perrin, &c --- to say "this is all totally sane, and if you buy the premise of NaCL, go ahead and use this instead.

You'd also really like Sodium to say "this is as much as we're changing from NaCL and nothing else", because what makes NaCL worth building on is the expertise that went into designing it in the first place, which, like me, Frank Dennis probably doesn't have.