I believe it is interesting to begin with, but it is dependant in the type of person you are teaching. The course at parts I believe is aimed more at instantaneous memory, especially the number tests, whereas some people need more time to reflect and let it sink in. In addition, I believe there is a lot of consecutive tests, which for me personally as a reflector I began to lose interest and got fed up near the end.
Course was mandatory, pre course score was 100%. Condescending and patronising in some of the exercises (do we really need to do the same thing 100 times). Maybe pre course should be done before actually doing the course and pretty much a waste of my time unless of course this is a smoke screen for some sort of MI5/MI6 recruitment (what other purpose does transferring 15 digits in 3 seconds serve) in which case I'm an obvious candidate for the job! Greg tried hard to keep people interested etc but could make it more competitive by creating teams and prizes or more interactive.