It is compatible with the windows mobile bundled software (Pocket Outlook), but it is different because:
- It is more flexible.
- It is designed to have the most used functions only a click away.
- The task list can hold more tasks in a single screen because of smaller font.
- Same for categories, and the list is scrollable.
- Icons on the menu bar, double click, no slow tap-and-hold and other nasty things like that.
- Keyboard shortcuts for most functions.
- Four filters to control task list contents.
- Quink insert mode: to create a new task, just type the subject and click enter! (v0.5 and newer only).

Planned features include import/export functionalities, advanced clipboard support, configuration and personalization, templates, cosmetic improuvements and others.

Update Description:
v0.6 (09-01-2008):
- Menus has been reorganized to be more coherent; two soft buttons instead of icons on the toolbar.
- Priority on quick insert has been added.
- Text prediction on quick insert has been fixed for mobile 2003, still losing the first letter on mobile 6 (don't know about WM5).
- New pretty icon! (thanks milkiller)..
- "enter" or action button were not working on category list in WM6, fixed..
- The "homepage" menu item wasn't working on WM6, fixed..
- The about box had a scrollbar even if it all fit..
- Made it a bit faster drawing.

v0.5 (17-12-2007):
- This version is compiled for Windows Mobile 2003 second edition! Tested to work up to Windows Mobile 6.
- Support screen orientation changes.
- New quick insert mode: to create a new task, just type the subject and click enter.
- Some keyboard shortcuts added: tab for categories, backspace for remove task .
- Newer versions of windows mobile insert empty subject on empty tasks, now supported.

v0.4 (06-07-2005):
- New shortcuts and hardware buttons: left and right arrows, change category back and forward.
- Context menu for tasks, activated by tap-and-hold or click-and-hold of action button (used for one-hand operations).
- Stats dialog, shows some info on tasks.
- New "Show all" menu item, resets all filters. Can be used before a "global search".
- Some optimizations on category list.
- Some buxfixes on category cycling.
- "Delete all" renamed to "Delete listed".

v0.3.3 (07-06-2005):
- Help file included now!
- If you assign a hardware button to OPTasks, clicking it when the program is in foreground will change current category.
- Ctrl-a shortcut reassigned to active/completed/all filter.
- Some optimizations, including reduced refreshes of task list.
- No bugfixes this time ;-)

v0.3.2 (08-04-2005):
- Added clear button on search dialog.
- Fixed a bug on category filter with values being a substring of an existing category.
- Esc on category dialog works now.
- Some code cleanups, smaller executable.
- Move (change category), shortcut ctrl-m.
- Fixed a bug handling categories with spaces in the name.

v0.3.1 (25-03-2005):
- Fixed a small memory leak (limited to the application).
- Show future tasks function (current, future, all).
- Added [f] indicator.
- Keyboard shortcuts: ctrl-space changed to just space, ctrl-f search, ctrl-t active/completed/all, ctrl-d current/future/all.
- Some task list speedups.
- Bugfixes.

v0.3 (08-03-2005):
- Homepage menu item.
- Toolbar tooltips.
- Filter by text (search).
- Active/completed/all (completed filter) + [c] indicator.
- Rename dialog, useful to see long subjects not fitting into the task list.
- Bugfixes.

v0.2.2 (19-02-2005):
- R (recurrent) and D (due) indicators added.
- "Delete all" function. Works on tasks currently listed.
- Accelerators (keyboard shortcuts) for most functions.
- Icons changed.
- Misc. enhanchments.
- Bugfixes.