I think that the late Rabbi Aryeh Kaplan was one of the most brilliant minds of the past century, certainly he was one of the top spiritual minds the world ever produced.
Meditation and Kabbalah is the second book he wrote on the subject of meditation-- behind Meditation and The Bible and in front of Jewish Meditation: A Practical Guide. First of all, Meditation as a subject is extremely vital, that is the basic (generic?) form. This is where is his other two books come in. However, meditating on kabbalistic formulas is not child's play and can be potentially dangerous if one is not aware of many spiritual realities. There is of course, this pop phenomena of making the kabbalah available to the mass population. This is not what Rabbi Kaplan would have agreed to. In fact, he explicitly states in his other books that advance meditation should only be practiced by experienced meditators and only with advanced guides to lead one back to the natural reality.
I've owned this book for five years and use it for, primarily, academic research. Please consult legitimate authorities in this field-- and not new-aged gurus-- before making this purchase.