Its a fairly good. The authors assign points for certain pieces. I still have the book but, have not read it in quite awhile.
point count chess

As far as I've seen there is only the Ishi Press reprint available with "old" (descriptive) notation which I simply cannot read easily.
You can find most of the key points here:
http://www.chess-game-strategies.com/point-count-chess.html
For me there are too many points to count and some topics I still don't get when to count or not (e.g. "Pawn on 4th vs. pawn on 3rd"). Even Kmoch with his strange naming convention gave me more improvement.

Here's what Dan Heisman had to say about the book in his Novice Nook column titled "Chess Books and Prerequisites":
"There are several classic “intermediate” positional texts. One of the most basic and unjustly maligned is Horowitz and Mott-Smith’s Point Count Chess. If you ignore the point count method and just study its examples, it is a great, but alas out-of-print text." (The article was written in 2001, before Ishi Press came out with its reprint.)
https://web.archive.org/web/20140626180930/http://www.chesscafe.com/text/heisman06.pdf
What do you think about this book?