Both this book and the Institutional Powers book by the same authors are used at my University for the Constitutional Law courses. It is, as most law texts are, a little dry, kind of dull, and a whole lot of information crammed into a thick book in small type. That being said, Epstein & Walker succeed in making the information more accessible than any other textbook I've had to use in my studies on the same subject matter, and include photographs on major cases to help students place the information. They also contextualize the case information, giving the technical explanations and following with a more colloquial summary to ensure that the major points are understood.
The books do tend to be on the expensive side (in the realm of PoliSci texts, anyway), so if you know you're taking the class and if your school, like mine, uses this book across the board, it's best to buy it in the middle of a semester when those who have dropped are just trying to unload the book as quickly as possible. I managed to find it for under $35 on Amazon where it usually retails for around $75 (still significantly less than campus bookstores, even for used editions!).