An interesting review of the Muslim Brotherhood, under the theme of 'Is the Muslim Brotherhood a terrorist organization or a firewall against violent extremism?' by a US academic:https://www.washingtonpost.com/news/monkey-cage/wp/2016/03/07/is-the-muslim-brotherhood-a-terrorist-organization-or-a-firewall-against-violent-extremism/?

He concludes:
The Muslim Brotherhood’s firewall against extremism, therefore, was a very real thing in the decade following 9/11. It was sustained by the seeming success of the strategic choices by the leadership, a robust organizational structure able to enforce internal discipline and the socialization of its members into the organization’s norms. All three of the key mechanisms by which the firewall operated have now dramatically eroded.
This does not mean that the Brotherhood has been or is becoming a terrorist organization. It does mean that earlier assessments of its ability to play a role as a firewall against violent extremism need to be updated.