This was our Korean 102 coursebook at UBC; the main author King was/is head of the Korean dept. I've given it a mediocre rating because it's simply really nasty for self-teaching, and like most language-learning textbooks, pedagogically challenged for course work as well.
What it does have going for it is its magisterial command of the language exposition proper, by two senior Koreanists and linguists. These guys have a half-century plus of knowledge about the language, and it's one of the top-tier textbooks anywhere.
Here's the good part: the whole book's entire material is represented on UBC's Korean site, and it's much better to go there and start in on Korean! (You don't need to sign in [at present, anyway], just go to korean · arts · ubc ·ca/online-textbook-korn-102/ [fix the dots, I don't know what goodreads does with live links] ) Everything instructionally rotten about the book is circumvented. There are lessons, exercises, audio clips, audio dialogs, etc. etc.
So don't waste money on the book. The workbook is pretty mediocre, so don't buy that either.
Also: the audio (both on the site, and the book's CD) is scratchy. It's in the original, so don't think buying the whole book and recording is going to get around that. That said, the audio is tolerably noisy. It's not like the Apollo moon-landing transmissions; you'll get used to it.
Finally, something you cannot do with the physical book, is copy-paste the dialogs from the site into Google Translate. This will give you a (crude) translation and transliteration, and surprisingly decent audio rendition. If you are particularly adroit with a Mac (or you can ask someone who is) you can rip the audio parts and do looping-repetition drills with words, phrases, sentences, and dialogs on your favorite audio player/editor, such as Wavepad or Audacity or whatever. I'm particularly fond of back-chaining looping practice, and if you've never heard of back-chaining for all kinds of things, I recommend you Google it. It originated in U.S. army language practice as far back as WWII, and yet is mysteriously one of the best-kept secrets of not only language-drills, but memorizing scripts, music passages, and who knows what else.