Should I still feel obligated?

I requested a book for review. It was listed as a physical copy paperback. Instead, I received a ebook. I only wanted this book so I could read it at work. Some of the individuals I work with have behavior issues and don't take anything that cost any decent amount of money when I am working with them. Should I still feel obligated to review it? It is too "heavy" of a book and I was going to read it on nights when I work 3rd shift. At home, I don't get much time to concentrate on something that needs my undivided attention.