The Unofficial LEGO Mindstorms NXT 2.0 Inventor's Guide by David J. Perdue with Laurens Valk (No Starch Press) is an excellent book for the NXT robotics hobbyist to add to their reference library. It offers something for every level of NXT robotics building and programming. It is a learning guide that will take the beginner who has some experience with the NXT system, to the immediate level, to the advanced level builder/programmer.
There is a nice introductory section (Parts I & II) to the consumer version of the Mindstorms NXT 2.0 followed by some good building tips for sturdy structures and an excellent tutorial on gearing.
Part III covers the basics of programming with NXT-G, followed by using the NXT-G tools of calibrating sensors, updating firmware, block import, creating “Pack & Go”, plus the awesome tools of image editor, sound editor, and remote control (which are only found in the consumer version of the software).
Part IV covers the projects. The projects are presented in a progressive sequence from beginner to intermediate to advance. The first project, “Inventor Bot” is a nice example of a robot using treads and is easy to build. The “Sentry Bot” takes the Inventor Bot a step further by adding an Ultrasonic sensor, a third motor, and a ball-shooting device targeting the object (intruder) that is detected by the Ultrasonic sensor. Pretty cool! The “Table Bot” adds two Touch sensors to sense the edge of a table: and the Ultrasonic sensor and third motor can be removed or remain on the robot and programmed for some function. With the "Table Bot" the level of programming could be considered intermediate. The next two projects, "The Jeep" and "The Lizard," offer two new designs for building, which will make use of Color sensor. On the advanced level is the last project, "The Printer: a drawing device."
Overall, I found the building instructions clear with very good diagrams, I particularly liked the "blow-up balloons" to show detail. The programming diagrams were also very good with the use of labels to explain. Besides being a great reference for the hobbyist, The Unofficial LEGO Mindstorms NXT 2.0 Inventor's Guide also a great guide for teachers of NXT robotics.