I needed a textbook for my contract law exam that was specifically geared towards the theoretical part of contract law. Contract Theory was an absolute lifesaver, it explains in an excellent, easy to understand way the will and reliance theory- which was a major part of my course! Most standard textbooks hardly ever touch these theories in detail and the only way to actually get to grips is to try to read C.Fried 'contract as Promise' and P.Atiyahs 'essay on contract'- both which are time consuming and quite hard to read, especially if your in the first year and just about getting to grips with how the law works.
I would thoroughly recommend this book, It enabled me to write a great essay in my exam. My only regret is that i bought it quite late in the course! Buy it if your studying contract law! Its brilliant!