What are some alternatives?
WorkFlowy - WorkFlowy is an organizational tool that makes life easier. It's a surprisingly powerful way to take notes, make lists, collaborate, brainstorm, plan and generally organize your brain.
Dynalist - Dynalist is a web app that lets you break down and organize your thoughts in the format of lists.
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
Checkvist - Checkvist is a tool to create and share checklists, plans, and outlines.
Trello - Infinitely flexible. Incredibly easy to use. Great mobile apps. It's free. Trello keeps track of everything, from the big picture to the minute details.
Orgzly - Outliner for notes, tasks and to-dos