It's easy to use out of the box and there are lots of ways to slice & dice, but navigating the many (many) reporting options does take time & patience. Nevertheless it's a great tool if you have the time to learn it.
I use Trello for bug tracking & product development in two companies and as a to-to list management tool, personally. Feature rich yet with a clean UI. Easy to use from day 1.
Productivity has never been so easy or fun. Sometimes things move a little too fast but you can bookmark posts you need to find/come back to later. That feature is a game changer. And now that I can integrate my files in Slack with the rest of my stuff through Dokkio, and plug in calendar reminders, Trello & every thing else I use, Slack is my digital homebase.