I agree with the reviewer who said that it should not be used alone. Actually, what I am finding after trying to learn Spanish for business for about a year, is that there is NO single resource that can be used alone.
I travel a lot on business to various Spanish speaking countries and this is the book that I take along most often. It deserves a place in your Spanish-learning library.
My experience has been that to learn Spanish on your own, you need books, tapes, dictionaries, videos, Spanish TV, newspapers, PLUS you have to practice, practice, practice with native speakers. Every type of resource you can think of. If you want to learn quickly, move to a Spanish speaking country for a year and devote the year to learning Spanish. Otherwise, it will require persistence and patience.