Saltstacks is a powerful and robust remote execution tool
Saltstack started its life as an execution tool. It gives you the ability to execute commands across thousands of servers with scalpel precision.
Saltstack employs a job id system. Jids can be referenced and tracked after they are executed. They are even stored in history and can be referenced later.
Saltstack employes zeromq to send out messages. This means that it is infinitely scalable since the saltmaster is not opening up thousands of SSH sockets with minions. This is an important distinction to other tools such as capistrano, which are bound to fail during large deployments or when network connectivity is spotty. Plus, because of the jid system, you can keep track of what's running, what's failed, what's succeeded, and what's finished.
Saltstacks using simple ssh keypairs for authentication.
No juggling SSL certificates. Each host has a private and public key. Using these keys both the master and the minion can verify the identity of the other.
Saltstacks configs are stored in a readable yaml format
Unlike both Chef and Puppet -- which store configurations in a Rubyesque way -- configurations in Saltstack are yaml and very easy to read. You can also use simple yaml parsing programs to check the syntax of your configuration file.
Saltstack provides top-down execution order in configurations
This is something that drives a lot of people insane when using Puppet. Puppet manifests are executed in an declarative way that seems to just jump all around the manifest, so you end up writing dependencies for all sorts of executions. This leads to significant bloat of config files as well as some serious heartache when attempting to troubleshoot manifests.
Salt configs on the other hand are wholly imperative and will execute from the top down in an SLS file. This helps greatly when porting over bash scripts. It also means you don't need to write requirements for any declaration.
Saltstack has a lively and active development community
Saltstack is the new kid on the block and is generating a lot of buzz. Unlike both Chef and Puppet, the salt community is lively and active. Mailing lists are busy and users on the irc channel are quick to offer help. This makes a huge difference when getting help.
Saltstack will not try and sell you hosting
This was something that always bugged me about Chef. There is no paid hosting with Saltstack. Everyone gets the same thing. The developers are not just trying to make a buck but are instead trying to create a great tool.