This book has lots of ideas on how to design a garden that will look good all year round. There are basically four sections: winter, spring, summer, autumn. Each section gives info about plants that stand out in these seasons, and how to incorporate them into the garden. There is also a section on bringing all the elements together into a cohesive design, and an encyclopedia of plants at the end.
The emphasis is on choosing plants that contribute something in more than one season, and on designing the garden to have good structure and a variety of plants for bloom sequence. There are lots of little garden plans, some with pictures and illustrations showing how the same spot changes throughout the year.
My one complaint is that the author's plant choices and designs rely heavily on plants that are suited to her own climate (East Coast zone 7). Many of the plants are only hardy to zone 6 or 7 and need acidic soil and mild summers. She doesn't really talk about any alternatives for people who might be gardening in other climates. It would have been more useful if there were ideas suited to a range of climates, and/or ideas for how to adapt a plan for other zones.