It's too easy to gush about this book. The topic is how to display data to get the information across in the most honest and useful way. To tell that, you learn some history, see some very creative graphics and also see some very bad graphics.
For an example of very creative graphics, the book cover shows the 1880 train schedule for Paris to Lyon -- you can just about make it out on the cover shot: the diagonal lines in the top half of the cover. Time runs left to right, and stations run top to bottom. It's a very nice way to show time schedules in a compact form, with the bonus that the slope of a line show the speed of the train.
The book is full of these kinds of creative graphics, which makes it a pleasure for me to read. The guts of the book is really about guidelines for presenting data: keep it simple, remove anything you don't need, make every mark or spor of ink work, be honest, be inventive. Tufte even has equations for measuring the information value of one graphic compared to another.
By default Excel breaks just about all the guidelines. Maybe someone should start an open-source project to bring some of Tufte's guidelines into StarOffice.
Oh, the book also confirmed something I've long suspected: pie charts are stupid.
My rating: Recommended