Engineering a Compiler is an excellent introductory text on compilers. I particularly enjoyed the textbook’s clean layout and design and cleanly written algorithms placed very close to the paragraphs where they are relevant.
Particularly after reading Muchnick, I found the amount of text explanation with a lack of concrete examples to be disturbing. Whole sections pass without any accompanying code examples. While I didn’t think that pseudocode would have particularly enriched these topics, and I could certainly look up the relevant papers provided in the bibliography, I found the lack of a concrete representation to work with left me somehow wanting more. This may trouble other readers less than it did myself.
All in all I suggest Engineering a Compiler as an excellent candidate for easy entry into a discussion on compilers, or an undergraduate text. After reading this textbook, if you’re still hungry for more on compilers, try Appel’s Compilers in ML and Muchnick’s Advanced Compiler Design and Implementation.