We just started it, my DD is doing Book Store and my ODS is doing Pet Store over the summer. They really like it!
They really like that it is putting math into real world type experiences.
My DD is finishing Epsilon MUS and my ODS finishing Delta MUS and so far have been able to do the math in Pet/Book store with little help from me, which makes it that much more fun, it is their “project” 🙂