Tasks editable only by user who enters them
Although it is possible to enter tasks within OCM which are also viewable by other authorised users (if the Contact/Company/Deal is shared). The other users cannot edit the task, mark it as complete or see the end date. In addition if the task user marks it as complete other users still see the task as open. Ideally other users should be able to amend tasks, but at the very least should see completed tasks as completed.
David H commented
Agreed, what is the point in making tasks viewable by the team if the team cannot edit or update said tasks.