This book takes a structured, step-by-step approach to software and hardware development with the AVR microcontrollers. As such, it should have merited 5 stars.
But, it suffers from one minor and two major defects.
First, and least importantly, the writing style is rather variable. It's the exclamation marks that get me annoyed! This gives some sections a rather breathless gosh-wow feel to them!
Second, and more severely, typographical errors abound. While these will be obvious to many seasoned developers, the target audience of new AVR users will be flummoxed by them. One early section uses 320 ohm resistors (try finding them - the common value is 330 ohm), and repeatedly uses an OUT instruction to read a port value (it should be IN).
Lastly, this appears to be a based on Mr Morton's previous book on PIC microcontrollers, to the point that one of the appendices is headed "Table of PICs". This leads to some problems in the hardware designs, particularly with driving LED displays. The AVR can only drive LEDs reasonably well using one type of connection, and it is not the way that most of the LEDs in this book are wired up. Many of the designs omit current limiting resistors, too. This can lead to (at best) bad practice, and (at worst) dead chips.
I hope that these errors will have been rectified for edition 2.