2Do combines the best of the available task management / to do systems in the marketplace. It lets you use Getting Things Done (GTD) methodology if that framework works for you, but you are not limited by the GTD constructs like in some other systems.
2Do provides you the features to design the experience the way you like: for example, I use some GTD approaches, however, I also like tags and assigning priorities to my tasks. Being able to have both start dates and due dates is a powerful feature to organize your work so you see what you need to focus on. Filtering and sorting your tasks provides almost limitless ways to view your work, and they are easy to set up. Adding “actions” to your tasks is a great way to save a url, email address, phone number, Google search, etc. to help expedite accomplishing the task.
The sync process is best of class for this type of app… there are several options and you need to evaluate which will best work for you. It’s great that they are all relatively secure channels you control rather than a propietary vendor cloud service. I use the the Reminders CALDAV approach that uses Apple’s reminder service as the back-end… it’s lightening quick and lets me see my 2Do’s in my calendar (important for me), but like just everything about this app, you select how you want to work. The iPhone app is also great.
The key for me with 2DO (and I have used just about everything on the market) is the balance betweek flexability and power. Omnifocus is powerful, but I always felt a little lost and frustrated as I tried to work within their rather dogmatic approach. Wunderlist and Todoist were flexible, but lacked key features for me. Things, Clear, Todo, Carrot, RTM, Trello, Toodledo, etc. just never resonated with me. One area which could be improved is attaching files to a task… currently only images are supported, but other file types (or at least PDF) would be welcome.
Having used many tools, I highly recommend 2Do.