Yay, I'm brownish-purple! My favorite.
Honestly I had a bad attitude about this book when it was recommended to me. It just sounded silly. Now, halfway through, I love it! It's another useful way to slice up the personality pie, but in some ways is more helpful than the MBTI, and is also infinitely more flexible. I've already learned a lot about myself and family and friends that had been baffling me for years.
I especially liked the chapter on Characterization, the rounding out of your personality by purposefully adopting attitudes and behaviors from various personality profiles.