We are using concourse at work right now and have 50-ish pipelines for various repositories. IMO, there's definitely some work you have to put into it because you'll sooner or later run into a problem with the existing resources and need a custom one. Writing custom resources is pretty easy however.

Concourse also isn't really made to work well with the Git Flow, there is no builtin way to run the CI on multiple branches (there's a git-multibranch community resource which requires redis at some point). we're basically thinking about changing our workflow to trunk-based, but it still feels weird to me that we might change our workflow to fit our CI better.

that being said, I personally still really like concourse and it's fun to work with.