Defer tasks and Review feature are the best and nearly exclusive features of OF in the crowd of task

Expensive but worth it in my opinion
The two features above are really game changers in the Task Management crowd.
The Review features is critical for me because it forces me to go through all the tasks in all of my projects on a regular basis. It avoids having stuff lost in dark corners.
For the rest, the classic task management part of the feature is great of course. And I do not like web platforms my self, so I am very happy with OF.
Another very useful feature is the Perspective feature that allow you to have a specific and powerful filter on all your tasks (based on project, context, key word, dates, etc...).

In fact, Omnifocus is so good that it took over some of the things that I used to do with Evernote. For instance, it became my brain dump for all ideas I have on my mind. And, on the Mac software, it is quite easy to link any task to Evernote notes, Finder folder or files.

Ric/VdC/12345 about OmniFocus 2, v2.2.5