Salt is definitely more complex than Ansible. Ansible wins the simplicity battle by a mile - for small or low-maintenance setups, I'd go with Ansible. Salt is way less complex than Puppet or Chef, though.

However, once you have a decent number of things to manage, Salt becomes worth the initial setup cost, IMO. The hardest part about it is just learning the concepts - the difference between "states", "grains", and "pillars" is unintuitive, for example (states are what describe your system, grains are k:v data that lives on the minion, pillar data is k:v data that lives on the master), and it's not initially clear how states differ from modules (modules are "functions" that run, states wrap modules in a declarative syntax). Once it clicks, though, you have a seriously powerful tool at your disposal.

The perceived complexity often also depends on how you are using your current setup. For example, if you use dynamic inventory and lots of plugins, Salt doesn't look very complex. But if you use bare sensible with some static files, then it does indeed.