Several members are currently using them --- hopefully they will comment. There have been no glaring bad reports that I can recall.
I cannot offer specific recommendations as different firms suit different people, but I would avoid the large, faceless, firms and go for the smaller independants, where they take the time and trouble to see you as an individual.
My opinions are merely that .. opinions based on experience. Always seek professional advice.
IVA Completed 23rd July 2013 .... C.C. 10th January 2014 http://foggy.blogs.iva.co.uk