This book is composed by 372 (black and white) pages featuring 15 chapters, describing Blender 2.43 and later bug fix revisions in its essential features needed to start working with this wonderful piece of always evolving software. The book try to "hit" the biggest audience possible and it is tailored to three kind of people: those who are completely new to 3D and Blender, those who are new to Blender but have reasonable 3D experience (and maybe want to read the book for software evaluation)and those who already know Blender but need a refresh in their knowledge to fill the gap with latest Blender development.
This book has been written by well renowed Blender artists and chapters are packed and extended in a wonderful book by editor and lead author Roland Hess. Each chapter speaks its own voice, so you can read the book in a non particular order and they're divided in two parts: a tutorial part (in which you explore main tools and techniques with a "learn by doing" approach) and a discussion part in which more detailed concepts are explained, completing the topic with further advices and tips.
Chapters are grouped by topic (basics, modelling, animation and rendering) and they are:
Chapter 0: How to Get Blender and Install it.
Maybe this chapter is completely unuseful. If you're interested in this software, probably you already own Blender, you know where to get it and you know how to unzip/untar an archive or double click on an executable to install it (depending on your operating system). Fortunately, it's only 3 pages long and include a reference on where to get help when you need it.
Chapter 1: An Introduction to 3D Art (Roland Hess)
This 11 pages long chapter gives you a gently introduction to 3D art, how it is accomplished and what working with a 3D app means. It's short but still worth reading, especially for those who are completely new to the 3D world. It describes the main differences between triangles and quads (and their relationship), the necessity of materials to achieve realism, the importance of modeling tools and an accurate lighting description and the (very basic) principles of animation, keyframing and rigging. Read this chapter if you're new to 3D, you will surely be interested.
Chapter 2: The Blender Interface (Roland Hess)
As the title imply, this chapter gives you an overview of the Blender interface. Many new users gets frustrated with the Blender interface at first. This is no longer the case, as the chapter gives you nice informations on how to master the basic concepts to work proficently. After reading this chapter, you will finally appreciate this interface and you will be able to exploit the real potential of the efficient workflow it produces. Headers, the toolbox, the buttons window, orthographic/perspective modes, layout adjustments, all is covered here.
Chapter 3: Object Manipulation (Roland Hess)
No exageration, this is the most important chapter of the book. The material covered here will be used all over the book and it's a description of the basic knowledge to use the program and its main tools. Many important principles described here are the basis of most of the Blender tools. This chapter is structered in a way you will work through a simple Blender project, complete with a keyframe animation.
Main hotkeys and functionality are covered and it will touch concepts like undo/redo, the meaning and use of the 3D cursor, adding objects to a scene, moving/rotating/scaling principles, transform manipulators and their activation/use, mouse gestures, object duplication, what empties objects are and how to use them, object parenting, the snapping menu (very important), layer management, object constraints and the basic of keyframing animation. If you are new to Blender and 3D in general, this chapter will teach you the basics of working with a 3D modelling package. A very well written and informative chapter. You will be surprised on how many topics can be well covered in just 37 pages.
Chapter 4: Mesh Modeling (contribution by Kevin Braun)
How to produce complex objects with Blender using its modeling tools. I really enjoyed this chapter. You will build a complete bridge with wonderfully decorated pillars. You will discover various kind of selection tools fo verticies, edges or faces, how to effectively use the mirror modifier, how to subdivide objects, the art of the knife tool, object extrusion, a good introduction of the proportional editing tool, the loopcut tool, edge slide, edge loop/ring selections, the use of the array modifier and much, much more... Even experienced users may learn something new from this chapter. Personally speaking, I liked the technique described to pull vertices into inline. This is used everywhere in modeling but it wasn't described in any book I bought in the past.
Chapter 5: Multiresolution Sculpting (Tom Musgrove)
Multiresolution sculpting is an approach to mesh modeling that allows you to shape and add detail to a mesh by pushing and pulling polygons with specific sculpting tools (brushes), instead of direct manipulating vertices/edges/faces. Not much to say about this chapter, you will produce a nice detailed monster using the draw/layer/grab/inflate/pinch brushes. It will teach you all the tools needed for sculpt modeling, including informations on how to use a regular texture and transforming it in a brush. Mesh hiding to improve performance is also explained in detail. Advices and tips complete this nicely structured chapter.
Chapter 6: Character Animation (contribution by Ryan Dale)
Character animation is a huge field and not much can be covered in 23 pages. But this chapter make a tremendous good job in concentrating much of the key concepts of character animation in a good practical tutorial. You will produce a complete walkcycle and you will be introduced to various stages of the walkcycle poses. The Timeline Window, the Action editor and the NLA editor are the main actors for character animation production and they're well covered in this chapter. Inverse Kinematic (IK) and Forward Kinematic (FK)are also introduced. Good the choice of presenting character animation before introducing rigging/skinning concepts (which are concepts explained in the next chapter).
Chapter 7: Rigging and Skinning (contribution by Ryan Dale)
The natural extension to the previous chapter. All the basic knowledge you need to create a solid rig and hook it to a mesh is here. You will be introduced to bone creation/manipulation, bone naming and its importance, bone layers, parent/child relationship with bones, IK (inverse kinematic) chains, constraints usage and explanations like Locked Track, Copy Location/Rotation, Track To, Floor, Stretch To and the IK solver. The skinning part (hooking the final rig to a mesh) covers the main concepts like the Armature Modifier, envelopes, vertex groups and has a nice tutorial on weight painting too for a fine control of mesh deformation. Rigging/skinning is the essence of character animation and naturally not everything can be covered here. The only complain I do with this chapter is that it doesn't cover many useful constraints.
Chapter 8: Shape Keys (by Andy Dolphin)
Shape keys are the Blender implementation of what other packages call "morph targets" and it's a new implementation of what Blender called RVK (Relative Vertex Keys) and AVK (Absolute Vertex Keys) in the past. Very useful in facial animation, shape keys are the way Blender implements mesh deformation in a time aware manner (animatable). This tutorial teach you how to create/edit multiple shape keys and how to use them in conjunction with the action editor to produce mesh deformations by editing vertex keys in the action editor. And it does a good job in this. After you read this chapter, you will have full control of these concepts.
Chapter 9: Materials and Textures (contribution by Colin Lister)
The chapter I liked less. It stresses a lot on real materials observation (and this is right) but it gives little informations on the settings meaning. You will produce a "wood like" material and you will enrich it with a coffee stain. It left out many interesting concepts on material creation and this is a real pity. It does not even mention the difference of having two texture channels with the same texture and two separate channels with the same texture. Fortunately, the discussion part of the chapter try to fill the gap but it's still insufficient. I was expecting more from a chapter that's 30 pages long, to be honest. There is nothing about shader editing with nodes. What a pity!
Chapter 10: UV Mapping (contribution by Modron)
Suzanne unwrapping! Modron will guide you through the art of mesh unwrapping, a refined method for texturing complex objects. As an exercise, you will going to unwrap the Suzanne mesh (Blender's mascotte) using the automatic unwrapper (the easy method ...) exploring texture painting in the UV editor and in 3D view using texture painting mode. You will have fun with the live unwrap transform. Easy, informative and direct to the point.
Remaining chapters are a gentle introduction to the topics and are not advanced at all, but they give you the understanding you need to read more advanced material on these subjects.
So, from what I said so far, you have already understood we are speaking about a very good book to begin with, with many topics covered, useful to read more advanced documentation. A very good book, but still far to be perfect and these are the reasons why I give it 4 stars:
1) It doesn't cover scene management (link/append features) also known as "the blender database" and the obData system. This is very basic knowledge (and unintuitive, I would say, expecially the obData system) so it really should have been covered in this book.
2) Figures are (sometimes) really too dark to be useful. Fortunately they can be downloaded from the support site (*).
3) It has many errors. Not bad errors but still it has many of them (again, look the support site).
4) It does not cover many new features since the 2.3 guide, so its use for updating your knowledge is limited.
(*): The book has a support site that contains an errata, all images used in the book and some additional files to play with.
You can reach this site at http://wiki.blender.org/index.php/Books/Essential_Blender
Conclusion: if you are a new Blender user (new to Blender and 3D) you should buy this book without thinking twice. If you're new to Blender but you already know 3D, you should buy this book as well. If you know Blender and you have already read the 2.3 guide, you may want to skip this book and buy something more advanced and illuminating, like "Introducing Character Animation With Blender" by Tony Mullen, for example, if you're interested in animation or "Bounce, Tumble and Splash!" by the same author, if you're interested in physical simulations. New features can always be learned from the user manual on the Blender wiki, assuming you already have the basics.