John Petrucci's (guitarist of Dream Theater and Berklee-graduate) first instructional method focusses mainly on exercises and concepts to improve your guitar-technique (speed, accuracy etc), instead of just giving away a collection of licks.
The book is organized in segments like
"Warm ups (left hand)"
"Warm up (right hand)"
"Synchronization of both hands"
"Speed and Accuracy"
and he also deals with sequences, legato playing, sweep picking etc.
There is also a very interesting part at the end: Chordal techniques and orchestration, where John helps to build an effective chord vocabulary.
This book is recommended for all levels. Beginners can develop an exercise-schedule and find helpful and logical exercises to improve their technique, intermediates can find several interesting approaches to sweep picking and chord-arrangement.
One of the best methods dealing with technique-exercises and separating your exercise time in a schedule by working on all elements of playing. Perfect to develop long time-practicing-schedules. The "Chordal Techniques" section is the icing on the cake.
Prerequisite: Beginners especially should have enough motivation to really improve their technique, because this book contains lots of chromatic exercises. These sound quite mechanical but are very helpful when you work on your picking technique.
Most of these exercises demand a fair amount of time, so self-motivation is a must. Keep that metronome handy too.