What are the strengths and weaknesses of the Wikipedia approach to knowledge dissemination?

The strength of wikipedia approach is its huge member-contributors who answer questions, ask questions,provide necessary inputs, suggestions which play a pivotal role in knowledge dissemination. Well, the weakness I find is that there are very often repetition, silly questions being asked. When a person can quency any of his knowledge thirst, survival of these websites depnds on better monitoring and organizational power of the management.