I often search for comparison between two Japanese words on the web and on multiple occasions, I got hits from this (as a Google Book). I finally decided to get it...
First, the title is wrong and sounds dumb. It doesn't teach you "essential vocabulary" and except for one example given in the preface, there's no "embarrassing" mistake to avoid (I guess they thought it would sell better by playing on fear of embarrassment) The book is actually about correct word usage and especially distinction between similar words.
For example, what's the difference between , and Between and Between and and It can be difficult to find a clear explanation anywhere and the author isn't always perfect either... sometimes his explanations are a bit vague, but most of it is clear. The real value of this book for me were the unknown unknowns; subtleties I had never thought of, that do make a difference in meaning or that would be incorrect, like saying something is if it's pleasantly warm.
Of course there's only so much you can pack in 300 pages and I already knew the majority of it, but the stuff I didn't know would have been difficult to come across otherwise. So I think it's good for upper beginner to mid/upper intermediate and especially self-learners like me (who don't get as much info on usage as people taking classes).