>It looked a lot like a whiteboard with sticky notes translated into a web browser and an iPhone App. That's pretty much it. It was an insanely easy idea to copy, you can already do it with sticky notes if you work in an office. I don't really think you can improve the service beyond that; It's a note tracker, it tracks notes.
I've said this on HN before. But this is what I love about Trello - they resisted the urge to do more than just reproduce the sticky note/whiteboard experience digitally. I've used other products that could be described as "copies" that tried to "enhance" that experience, even slightly, with additional functionality that ended up detracting from the core product. It seems like that was a harder balance to hit than it…
The thing is that it is so limited, that you'll move away from it sooner or later when you need more structure. I've used it in a significant capacity in 4 teams, and we always ended up migrating to another tool, once it was clear which other tool would fit the needs of the team the best. Sure, that's good for you as user to have an early-stage playground, but probably bad for Trello.