We use this solution for product development and issue tracking.
This solution provides us with a centralized view of issues, simple time registration, and excellent integration to Bitbucket.
The most valuable feature of this solution is the source linking on the commit level to git.
The speed of this solution needs to be improved.
Backlog pruning and visualization are poor.
Uupdate:
Speed has improved slightly in backlog view with Jira 8.0, but there is still room for speed improvements.
It's difficult to group and manage the backlog and priorities on multiple simultaneous epics to get clear overview of how the backlog reflects a planned roadmap. (perhaps due to the fact that we have too many issues in the backlog)
We have been using this solution for seven years.
You are right that Jira is a great workflow engine with the ability to highly configure workflows, boards, pre and post activities.