There is indeed a lot of good material in that book. DeBecker himself is virulently anti-gun and has bought into the firearms prohibition propaganda wholeheartedly, but I suppose any one of us, growing up with shots fired at our heads by our own parent(s), would be a little irrational where that's concerned. (Still, it is something to consider. Self-defense advocates who believe in gun control should be viewed with caution, as there's a very real danger they don't know what they're talking about.)
His firearms bias aside, the book shines where awareness and mental and emotional preparation are concerned. It's definitely worth reading. Strong on Defense, by Sanford Strong, is another good one -- and the firearms caveat applies where he is concerned, too.