As a student of sociology, I have to say that this is a practical textbook, yet lacking in many aspects.
Ritzer tends to simplify some very important aspects of many theories. On the other side, he often pays much attention to less important aspects of grand theories.
I am not a passionate Marxist, but the lack of attention given to Neo-marxism is a big minus.
I am an European student and am therefore used to heavier literature, so this opinion might be biased. But in my opinion, this book oversimplifies important sociological theories. It can be considered as a kind of "popular" literature in this field.