Excellent depth and capability. The big dog of task managers for the Mac. Syncs well with the iPhone application, which also works well (if a little slow to sync and use). OF is a little austere in it's interface, and sticks fairly rigidly to GTD principles of actions, projects and contexts with no support for tags or smart folders.
Alternatives are
Things (which I personally don't find to be any use) and a newcomer in beta called
The Hit List, which I think is shaping up to be excellent, supporting actions, projects, contexts, tags, tabs, and smart folders. It has a really nice Mac feel to it, and once the developer fills in some missing features for the full release (like recurring action support and iPhone sync) I think it will be my preferred task manager. Also available for free is
iGTD which a lot of people seem to like, but which I never cared for.
Trial versions are available for all the above, so it comes down to which you find works best for your workflow. Hope this helps
