Given the heavy-duty subject matter, Brown's "Principles of Language Learning and Teaching" is probably about as good as it gets. It's definitely not a book of general interest, but rather a compendium of the various theories that have influenced and shaped the teaching of second languages in the 20th century. It's slow going, but after a one semester course during which I plowed through and digested the material, I've gained a general understanding of the theory behind the practice. Babyboomers like me who had an unhappy second language experience in school will smile while reading Brown's explanations of the theories of the 50's, 60's and 70's, and why so many of us became discouraged. As a teacher of ESL now, I can only say things have improved a lot. In this new edition, Brown has included a section in the last chapter on current hot topics in the field. But again, this is for professionals or students, not general readers.