I'm interested into learning more about interface design at the moment (still collecting book recommendations!). This book was close-by so I started with it and it works very well as an introduction to the basic concepts (metaphors, affordances, etc) as well as giving real advice on how to design the workflow of an application, what to keep in mind while doing so and some more detailed tips along the way on topics such as colours or the best font to use in forms. As usual Joel's style is pleasant to read, which makes this a very quick read. I definitely recommend this book as an introduction or refresher crash-course on interface design, while keeping in mind that in the end this is still only a high-level view of the whole process. You'll want to read more to answer more detailed questions and concerns about UI and HCI.