Yesterday an "insider" spoke and today the BBC has a - for them a quite long - report based on a defector:
One of the most senior figures to defect from Somalia's al-Qaeda-linked militant group al-Shabab has urged his former colleagues to stop targeting civilians and to begin negotiations with the Somali government.

Forming an alliance with al-Qaeda "was a very big mistake. Our duty at that time was only to liberate Somalia - our interests were local." He added that it had a huge effect and diverted al-Shabab from is purpose.
"Now it turns to terror acts, organised crime... we were against all that. In late 2010/2011 there was a lot of misunderstanding within the core leadership of al-Shabab... in terms of these terrorism events.
Link:http://www.bbc.co.uk/news/world-africa-32791713