I bought this book on the recommendation of a professor of Level 5 Spanish at NYU. That being said, I still have a long way to go towards fluency as a Spanish speaker. Consequently, Schaum's Outline of Spanish Grammar works for me. I was immediately impressed by the user-friendly format of this text. It's an appropriate breakdown of grammar for intermediate to advanced students, and for anyone motivated towards studying Spanish, whether auto-didactically, in a classroom context, or both. It took me a while to complete all the exercises, but it was definitely worth the effort [Chapter 3 (Verbs) alone takes up 79 pages of this 194 page book]. This text functions as a great review for someone who has already studied Spanish and who wants to brush up on whatever they may have forgotten. I think if one were to consistently use this book as a study guide, if they live in a Spanish-speaking city (even in the USA), knowing the grammar presented in these exercises would provide much-needed confidence for diving into the world of spoken Spanish. I am going to hold onto this valuable reference guide.
Stephen C. Bird, Author of "Hideous Exuberance"