I used ansible for building simple logging appliance (something like Elasticsearch + Dashboards + other tooling) and I found it very difficult to reason with specifically python code snippets within YAML.

Switched to Pyinfra and the difference is day and night. You write python code you can organise your stuff into functions, classes and whatever you like and then instantiate them as you like. Highly reusable configuration.

You have full pwoer such as you can call boto to fetch the list of servers to target, filter base on tags and what not. Only sky is the limit because it is NOT a DSL (or YAML) rather full blow real python.

Pyinfra is what ansible should have been. It's straight python rather than a janky mix of yaml, templates, and bolted-on control flow primitives.

I switched from Ansible to Pyinfra for my homelab, and continue to use Ansible at work.

The biggest difference is that Pyinfra is simply Python code. It's incredibly easy to control the system in whatever manner you need to. You can probably do the same thing in Ansible, but it's never quite as obvious how to do it. This also means it's much more clear where and why things work the way they do in Pyinfra, where in Ansible I end up digging through numerous role files to try to find where some variable gets injected.

At a previous job we used it to test our ansible playbooks via molecule, which were part of a CI/CD pipeline to create AWS AMIs.

It worked well and was nicer to deal with than test kitchen for testing UNIXy things (is service running and/or enabled, does file have right permissions, does file include $TEXT, etc). It was very useful for us during big linux upgrades, such as when ubuntu went from upstart to systemd. It can also be good at capturing edge cases with brittle outcomes (especially as ansible went through enormous changes after the red hat acquisition).

Dislikes? I had to fight with pyenvs a bit..