First off, I should point out that the word "cult" has become a loaded word that should be avoided at all costs. So often it is associated with everything from Jonestown to Waco, and nobody wants to believe that his church is a "cult." So having this word in the title could be a turn-off who are offended by such terminology. Working with groups that claim to be Christian but whose theology is anything but, I can vouch that Geisler and Rhodes do cover the major verses used to support false teachings. Although some of the passages are pretty much a repeat of what is covered in "When Critics Ask" by Geisler and Howe, there is enough original material to make it a worthwhile companion volume. It is especially useful for those who enjoy spending time sharing their faith with others. Of course, not every passage is as complete as I'd like it to be, but overall it gives the reader a head start in the right direction. For this reason I do recommend it.
Norman Geisler has written several "When ___ Ask" books. This is by far les exhaustive than the others, but that is this books strength. Aided by Ron Rhodes, formerly of the Cristian Research Insititute, this book aids a theologically correct Christian persepective on important scriptual verses that are often abused by cults such as Mormonism, International Church of Christ, and Jehovah's Witnesses.
The title, though "catchy", is somewhat of an offense because some arguably Christian denominations are also listed. Though the writers, Geisler and Rhodes, may not brand these denominations as cults, the title appears to lump them in altogether and to the person who already thinks that Roman Catholics or Seventh Day Adventists are cults, may also abuse the authors names in their assertions when discussing these issues with others.
The information, however is very accurate and the scripture commentary normally very sound and orthodox. This book is a good resource and only the title should have been changed slightly.
If you are a Catholic or Adventists, this book is also a good resource tool for you. Don't make the mistake of throwing the "baby out with the bath water." This book by itself, however, is not enough in understanding and dialoguing with cultist. It is a good supplemental tool and I believe the authors would agree.
I recommend getting Geisler's two other books of this same genre. They are "When Skeptics Ask" and "When Critics Ask."