I have not followed the system as prescribed, but I have not been able to stick to many systems...
I absolutely love Cardio Interval Burn & the 2 Cardio Strength workouts. I have not even tried the others, but I really should! I do need to modify some moves as well, but it is easy to do so and the time flies by.
I ordered mine directly from Michelle shortly after they were released and paid a lot more than Mary's price. I would still say I got my money's worth out of them!