Had to do the same thing but had a different experience. It was hard to dive in and took some time but now I understand and appreciate the core concepts. There are many abstraction layers ("[...] schemes") and IMO that is a good thing. When you customize workflows etc. you can do that without leaving supported areas. Creating and changing a workflow is very easy. Plus, JIRA has a good pricing.

With ~350 employees and many mixed teams using only Trello would be chaos. In key areas we need fixed workflows (-> JIRA).

Right now we are planning to add Wekan (FOSS trello clone) to our toolchain for workflows which are more dynamic (less "C follows B follow A" + smaller teams - e.g. innovation and some planning).

I consider JIRA a code smell: if an organization uses it, I probably won't be satisfied working with them. I don't think it's because of anything especially bad with Atlassian (although I was furious when they removed the ability to edit Confluence in raw mode), as that the managers I least want to work for seem especially attracted to it.

Your comment just illuminated that for me and I think you're right. It's the micromanager's dream, but for good managers it doesn't seem to offer enough over the competition to draw them in. The best I've worked with considered PM tools essentially fungible, and therefore weren't likely to invest in 1) paying for the Atlassian suite or 2) the overhead of getting it up and running.