I've also learned the first 1500 characters using this book, not in one month though. The method works but has some problems. Maybe the biggest problem is that it completely ignores pronunciation. It does not help you remember the pronunciation and it does not make use of the sound components of the characters. Most characters are composed of one component which hints at the meaning and another which hints at the sou…
If you're learning hanzi you can take advantage of the pronunciation hints. Plus the fact that modern hanzi generally have only one pronunciation per [traditional] character, and only one syllable per, too. The characters made so much more sense learning Chinese.