Wikipedia assignments are rewarding, but are in several respects more challenging than traditional assignments.
Demanding of students — Students typically find Wikipedia assignments more challenging than similar traditional assignments. They must not only research and write as they would normally, but also learn how Wikipedia works and how to follow its rules and norms. Also, the stakes feel much higher when students are writing in public.
Planning ahead — Instructors must plan Wikipedia assignments well ahead of time, since it takes a bit of extra time to coordinate with the Wikipedia community. For instructors who are new to using Wikipedia in the classroom, this is essential to a successful project.
Pacing — Students have less flexibility in pacing their work, since some critical elements involving feedback from the Wikipedia community will not be effective if rushed or put off until the last minute.
Grading — Especially for instructors who are new to Wikipedia, there is a modest learning curve to devising an efficient grading rubric, and assessment of student work may take more time than it would for a traditional assignment.