Hello,
There is a recent Gallup survey article about revisiting the matrix organization published on January 2016 which involved 4000 US employees highlighted some benefits in matrix organization. Survey categorized as matrixed, slightly matrixed, non-matrixed, supermatrixed employees working in such organization. Supermatrixed employees were generally twice as likely as slightly matrix ones to say it helped them perform better, collaborate more effectively with coworkers, serve customer well, and open up for innovation. On other hand, employees in the matrix categories complained not having clear direction and spending their days responding to coworkers’ requests and attending meeting. Due to this factors, in the critics’ assertions, matrix structure can slow decision making, stifle productivity and hinder organizational responsiveness and agility.

Reference
http://www.mckinsey.com/business-functions/organization/our-insights/revisiting-the-matrix-organization