I bought this guide after purchasing Resnick's 1001 Most Useful Spanish Words, which is an incredibly bargain at [price]. Essential Spanish Grammar, at [price], isn't so bad either EXCEPT for a critical need for updating in terms of pronouns and verb conjugations. In the 1950s, when this guide was written, it was a given that one did not use the familiar "you," so Resnick ignores it completely. Of course, these days it's "tu" not "Usted," and someone, perhaps Resnick's editor, needs to acknowledge that with a revised edition.
Somewhat lacking
Rating: 2/5
This book isn't bad if you consider how thin and cheap it is. It sacrifices completeness, emphasizing learning in a short time "what you'd be most likely to use." It completly omits using "tu", claiming that one only essentially needs "ustedes" (a bit annoying). Overall, it does serve its stated purpose of serving those with limited learning time.