A brief self-evaluation report is avaialble here: https://www.publishers.org.uk/activities/inclusivity/specialists/megaphone/report-on-megaphone/

There is a full evaluation report which you can request from Leila at megaphone.write@gmail.com 

Avantika Taneja has written a report on her experience as a mentee here: https://www.publishers.org.uk/activities/inclusivity/specialists/megaphone/graduating-from-megaphone/
On the blog, you can see interviews with the 2016 – 2017 participants. You can also listen to two of the participants talking about their experience of Megaphone on the Brum Radio Book show: skip to 14:00 to hear them.