First things first: the art is all, pretty much, amazing. One of the things which really made the original Star Wars trilogy special was the amazing settings, the fully realised worlds, and the costumes, and most of these are detailed here. But there is much more detail than that. This volume describes the process behind designing and animating the Tauntaun, the construction of Dagobah and the animation of Yoda, and the way in which matte paintings were used to enhance the sets. Perhaps the most interesting part deals with some of the details of life in Cloud City, its social structure and organization, and the depth of detail which went into its design. The art in this section is particularly fantastic, inspired by 1920s art deco styles and featuring a lot more depth than the film itself. I also enjoyed the fact that most of the production designs featuring Leia gave her the Danish-pastries hairstyle she wears in A New Hope.
The book is not without its problems. While the art is amazing, some of its presentation is quite poor. In the 1994 paperback edition which I read some of the larger pictures spread across two pages, obscuring part of the picture in the page divide. Other pictures are presented just a little too small. In terms of content, there is a considerable lack of detail to the asteroid field sequence, which was one of the production areas in which I was most interested, and there are no design sketches of any of the bounty hunters besides Boba Fett (perhaps they thought they didn't need that scum?). Perhaps also it would have been of interest to include more screenshots of the finished production for comparison - although I admit that these comments are now reaching the point of saying that the book simply should have been longer.
Nonetheless, the volume is generally fantastic. I borrowed this copy from the library, but I would certainly like my own.