Trello is an amazing product. Created in 2011 out of an existing company, it eventually was acquired by Atlassian for $425 million. How could an web application like Trello command a valuation of $425 million? How can a website that allows you to create lists of lists be so valuable?
Good timing great execution
It also was the first of its kind to use "Kanban" structure of information available to widely to users. This enabled it to remain a horizontal product: anyone across any industry can make use of a lists of lists. Just like anyone in any industry can make use of tables (excel) and an array of images (powerpoint).
It was also early in its adoption of application integration. Power Ups, or integrations via the trello API, allowed users to integrate their Trello boards with your calendar, to-do lists, or any other applications you might use.
Ease of use
But ultimately, Trello is just easy to use. And better yet its enjoyable to use. Anyone can start without much hassle. It's intuitive and simple. You almost want to create new boards, new tasks, new tags, just to delete them again. It not just solved a painpoint in how we can best organize our projects and tasks, but it made it fun to do so.
For products with a freemium model, where users can start and remain free, Trello is the north star. And as products become easier to test, faster to build, it will be the user experience that will differentiate products.
It won't be how useful is your product, it will be how enjoyable is it?