I found it to be very much worth my time! I'm sure there are a lot of people on this forum that share my opinion, and then again, there may be some who don't.
The system itself is great, in that it provides a ton of fun opportunities that can be very profitable - it's the way that people use the provided opportities that determines how much worthwhile will it be.
I hope you find the system, and mystery shopping in general, as useful as me and a lot of others have. :)
Don't hesitate to ask if you have any questions!