Pro Nice and simple user interface
Nozbe is based on Getting Things Done (GTD), a productivity philosophy created by David Allen. However, you don't need to know the methodology to use the tool. You can just add projects, tasks, and attachments, and gradually learn to use the other features to organize your time even better.
Con Task dependencies missing
Nozbe is great, but one shortcoming relates to "task dependencies" in projects. You should be able to sequence your tasks so that, when you complete a task, the next one that needs to be done becomes the "priority" task for that project. This is a vital feature that will make the program dramatically more useful. The company claims to be working on this improvement.