This is a really great book in the same high quality that you'd expect from any book coming from DK Press. The pictures are beautiful and plentiful. There's also plenty of information on what exactly that spice pairs well with. This means that if you bought the spice for a specific recipe, but don't know what else to do with it, you can read the notes on what it pairs well with, and experiment with other recipes that contain those flavours. Basically, this is your roadmap to spices, and it couldn't be more pleasant to use.
This is a reference book that's rather useful to have on hand, especially if you're interested in trying new spices that you haven't tried before. There are times when a cookbook calls for a specific spice, and you're not sure whether you should bother going to the store and getting it, substituting something else that you have around the house, or leaving it out entirely.
The point is that recipes aren't always very specific on how to substitute, or even if you should. With Herbs and Spices, you've got a good understanding of how the spices behave. For example, the section on tamarind describes it as having a sour, slightly sweet taste. If a recipe calls for tamarind, but you don't have it, you can substitute based on that understanding. If there's a lot of tamarind in the recipe, you'd go out and buy the stuff. If there's just a little bit, you'll know what it is you're trying to reach with the addition of the tamarind, and can adjust as necessary.
What I love about this is that it's opened up my world to sharing different spices in my own recipes than the ones I normally ask people to use.