Large Group Teaching and Textwall

file0001330166183I have been working with Chris Wise and Ed McCann at UCL to help develop the approach to teaching Design to budding Civil Engineers. Whilst I have lots of experience  working with learners, this has been  in much smaller groups and I am recognising the particular challenges of  working effectively with groups of 50 and more.

I have recently heard about a piece of software called Textwall. You will find more information about this tool here and I am very interested in hearing from anyone who has experience of using this tool as a teaching aid.  How effective is it in encouraging active participation in large groups of learners?  Are there any drawbacks?