They are definitely a big-name firm, but some of the advice they have rendered my employers (Both my employers over the past few years have utilized their services exclusively) over the years has been sometimes been downright wrong (unnecessary H1 re-stamping, AOS Vs CP, etc). Not sure if this is due to ignorance, or a deliberate desire to prolong the process (and therefore more money for them - extensions, mutliple documents, RFE's, etc)
To give the devil his due, haven't yet seen/heard of any rejection for a case processed by them - but then again, they seem to only deal with big corporations anyway.