We are a small (two-person) company working in different offices, and PL makes it easy to pass projects back and forth and track progress asynchronously without having to be in the same room. At a glance, it’s easy to see which tasks are emergencies/urgent (red label), current/ongoing (yellow), or upcoming/low priority (green). The percentage slider is a surprisingly intuitive way of grading progress and giving us a better idea of where we are from a timeline standpoint. And the simplicity of PL makes it easy to mix up large projects and smaller tasks on the same list so that nothing falls through the cracks.
It’s easy to ask for more bells and whistles from a project manager, but we’ve found that the complexity of the more feature-heavy web apps makes them a burden to use. Maybe an option to "turn on" certain advanced features would be nice, but I'm guessing that's not the developer's intention.
After trying out a handful of other project management tools, we found Project List to be just the right mix of features and simplicity for us to be inclined to use it every day. We prefer to minimize project management and focus in on the work itself. Project List makes that possible.