In general SOS is two full grade levels below the state curriculum (and I live in a low performing state).
In spite of this, it manages to be difficult because it is written in a way that is NOT user friendly. I think that in the social studies and English SOS intentionally uses big words to hide the lack of academic standards.
While, I will grant, it is easy and takes little prep time, it will more likely deprive your child of an education, than help him excel.
I believe that Christian programs should have the highest, not the lowest, educational standards (remember Daniel was 10x wiser than the other astrologers).