Beautiful close up photographs - and they are - may be a delight in themselves but they do little for gardeners who want to know what a plant looks like as a whole in a real context. The text was not detailed enough on information for keen gardeners, like origin of the plant, soil conditions, habit, hardiness ratings, etc.
This is an elegant picture book with clear basic information, and a very nice one at that.
It's not for you if you want a detailed handbook on selecting and growing grasses in your garden, in line with other RHS encyclopedias.