I’m only giving this book 3 stars because although the author makes an admirable effort to explain the technology in detail, and although the book does have a lot of useful information about devices such as Bluetooth LE, it can be frustrating to use. The overall approach to building and programming is difficult, and the code provided has errors or in some cases does not work at all. As a result, beginners are likely to be extremely challenged working through this book. Here are some of the problems I encountered along with fixes if I found any.1. Chapter 3 introduces FreeCAD and shows how to model the robot car. FreeCAD is powerful but difficult to learn, and it’s not necessary to build this car, as it’s only used to create a “technical drawing” of the chassis. All you need to know are the dimensions of the chassis and the locations of the mounting holes for the motors and the caster, and that’s provided on page 79. If you want to follow the instructions and learn FreeCAD, be aware that the author failed to mention that you need to create ShapeBinders for all three subassemblies. Also, you can save time and expense if you buy a chassis kit with motors, wheels and platform for $15 or $20, and avoid having to score, snap and drill a styrene sheet.2. Because of the choice of CircuitPython, the motor encoders must be read using the Raspberry Pi Pico PIO, and the PIO must be programmed in assembly code. The PIO has only 9 instructions, and they are not intuitive; for instance, there is no ADD instruction, instead you must invert the bits, subtract, and re-invert. Not something most beginners will have an easy time understanding. However, the author does provide working code to read the encoders, so you can just import that file when needed.3. The dimensions for the distance sensor brackets do not match the current VL53L1X sensors now shipped by Adafruit. Don’t build or 3D print the brackets using the information in the text.4. The code for the distance sensors needs a check for the “None” value returned by the sensors if there is no obstacle within 4 or 5 feet, otherwise you get a TypeError and the robot won’t run. Also, the uart.write calls in the Bluetooth section have a syntax error; there is a second “f” which must be removed for the code to run.5. Up through Chapter 8 all of the code worked perfectly, including the obstacle avoidance algorithm. In Chapter 9 the Bluetooth code worked well, except the left and right keypad directions were reversed. The wall-following code in Chapter 10 did not work at all, in spite of many hours of testing and debugging. In Chapter 11, driving a known distance worked perfectly, except that the robot ran backwards instead of forwards; also it’s not mentioned that you will need to install the circup utility if you want to use it. (The preceding three problems seem to be related, but I could not figure out how.) In Chapter 12 the procedure and code given for calibrating the IMU did not work at all, and as a result the always-face-north code did not run because it first checks the calibration.6. Just to be fair, although the illustrations in the print version of the book are in black and white and difficult to read, if you download the Color Images file, those images are excellent and especially useful for wiring. Also, the publisher will provide (with proof of purchase) a *.pdf copy of the book, handy if don’t have the physical book present where you’re working.In summary, this is a great book to learn about robotics if you have the time and experience to work through its shortcomings. However, this book requires more effort and experience than a beginner is likely to possess. If you’re just starting with robotics, a better choice would be to just use an Arduino board with the much simpler robot code which you can find almost anywhere online.