It can be used to implement more deep ideas such as Kanban, but these aren't forced on you.
I remember before Trello came out I needed an app that provided a list of lists (who doesn't). I designed it all out but never implemented it. I saw how much competition there was in the space. There are hundreds of tasks list and to-do apps out there.
So when Trello was announced I secretly scoffed at them thinking they were doomed from the start for choosing such an obvious and already implemented idea.
Still I signed up and started using it. It has been fascinating to see the app evolve and become a huge success. I only feel a little bit miffed that it was something I almost did myself since I know I would not have implemented it anywhere near as well.