I disagree with all the glowing reviews, and seriously doubt any of the reviewers started from square one and felt they were prepared to visit a Spanish-speaking country from it alone.
Pimsleur does have a great idea, inspired by the Foreign Service Institute's approach, but the thing is it takes TIME. What's good about the method is you're drilled and drilled and drilled... what you learn here will stay with you a long time.
The flipside (and it's a big one) is that with all that repetition, you learn almost nothing. You'll learn the numbers (up to a hundred), how to tell time, how to order a generic beer (almost every lesson spends considerable time on this), and how to ask where a hotel or restaurant is.
But if the hotel is not "right here" or "over there," (the only possible answers, apparently) you'll have no clue. Forget about "turn left at the intersection and continue for two-and-a-half blocks." You can order a beer, but forget about a salad, the daily special, what the waiter recommends, a steak, some chicken, or tea or a soft drink.
You can go shopping but unless you want to buy "things" you'll come back with nothing. Nada! "Cosas" [things] is the only thing covered! Forget shirts, dresses, pants, maps, guides, film, cameras, books, hats. Forget about buying a plane ticket, a train ticket, asking for help, asking what's playing, finding the beach, a nightclub, a doctor, a cop, or even checking into the hotel that was conveniently "over there."
To get any truly useful survival skills with this approach, these eight disks would need to be followed by at least a hundred others. And with three hundred disks practiced over two years, I have no doubt you'd even be able to converse on a variety of topics, which I believe was Pimsleur's intention. But Pimsleur's eight disks is so tragically short of qualifying for tourist survival Spanish, that it's comical, as long as you're not the one using it.
There are better ways to learn, but they will require more effort on your part, such as drilling yourself on phrases, learning vocabulary, and (gasp!) some grammar. I would recommend Easy Spanish Step-By-Step for grammar and essential vocabulary, and probably Teach Yourself Spanish Complete Course (Book + 2CD's) (Teach Yourself Language Complete Courses) (or Teach Yourself Latin American Spanish Complete Course) for audio, and adequate survival phrases. For getting beyond very basic, stock phrases, listen to the podcasts at notesinspanish.com. Don't neglect the multitude of other resources available to you there and elsewhere on the Internet as well.
Pimsleur's disks are still quite useful for practicing the sounds with time to repeat ... I'd recommend borrowing them rather than buying if that's an option. If not, you might try the course that inspired Pimsleur at fsi-languages.com, which is completely free.