Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Good intro book to accompany a course

I have had the privledge to use this book for an introductory course in differential equations with colleages of Dr. Boyce. This book is well written and contains numerous examples and a plethora of problems. However, a student would do well to have a very firm knowledge of calculus and a quick mathematical mind; some of the methods covered are not candy coated to go down easier. As such, it is important that a strong professor and a strong curriculum accompany this book. This is NOT a good book for self-instruction. However, it is a very useful reference to go back to when dealing with more advanced mathematical topics.