Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Hard to "Digest"

Hammer's is a very advanced grammar book NOT intended for anyone with less than university English grammar knowledge.A great extent of the examples encompassed within the book are solely in German with no interpretation in English. And that is a major flaw. Some of the explanations can be quite confusing and unintelligible so beware. Furthermore, one should take into consideration that that it serves the function of reference, excluding practice. Therefore, it is insufficient for students in need of practice. In the overall, not very useful for freshmen students.