The process described is reasonably robust in inexperienced hands. A more skilled facilitator will get better information by asking better probe questions and by making more efficient use of time. Even in the hands of an inexperienced facilitator, however, the process will usually yield good quality information. In the form described here, preparation is needed. However, as most of the important differences with structured focus groups are in the group session itself, that is the main emphasis of this description.
Detailed descriptions are available in a number of works.
In particular, Sage publishers have brought out a number of high-quality works on focus groups as a qualitative research tool. The bibliography lists three of them. There will also be follow-up work, typically writing a report and circulating it to interested people. The design allows for the introduction of other information for which a response is wanted. This is fed into the conversation part-way through the process.