This is a great book for more in-depth information. It's pretty deep for most gardeners, and beyond the scope of information they are looking for. However, if you are studying Botany, it's the most informative book I've bought.
If you are just starting to study botany, I would suggest first picking up a copy of Botany in a Day. That will give you a little background information so you can better understand the concepts in Botanical Latin.
I garden for a living, running a tiny landscaping co.. I could not live without this book. I use it to look up the meanings of latin plant names, this helps gain insight into a plant. It is not a must on every shelf, but if you are in the business, it's a helpful addition. I use his dictionary of plant names to help with spelling.