It really depends on why you want the book. If you only want it for the information provided by the written word, then the B&W is fine. If you only are interested in a breed that has black and/or white feathers, and don't anticipate ever wanting any other color or breed in the future, then the B&W is fine. But if you think that you would get benefit from the color pictures (they're drawings, but quite good ones) then the color version would be best. Plus, the color version is wonderful just to look through and let your imagination run wild. But it really comes down to what you need vs how much you are willing to spend for the extra perk of seeing a bird's ideal color.
One benefit that I could see of the B&W version is that all breeds would look somewhat alike other than pattern and shape. So if you are a new breeder and want to train your eye to the proper conformation of an individual breed, seeing so many subtle differences in one place, without the obvious distraction of color, could help you develop that skill a little faster.
