This is the second book on TGE by Ed Maurina. Another review noted it does not cover as much. True, it is a little smaller, but I think it is intended as a follow-up to the first book (The Game Programmer's Guide to Torque). It covers some more advanced stuff than the first one , and assumes the reader has some knowledge from the first book. I read both and own this one; I regularly go back to it as a reference. It clearly explains the client-server model of Torque (necessary knowledge, important even for single-player games) as well as Torque's much-praised networking system. The concepts of DataBlocks and NetGhosts can be tricky, but Ed makes it easy to understand. Bare in mind, some of the more intricate coverage of datablocks is in the first book, so I recommend getting both.
It also gives a rundown of the engine code, covering the basic classes you typically work and how to create your own classes based on them. Finally, there is some very valuable info on debugging and performance tuning via profiling.
Ed's style of writing is in-depth, but still accessible; easy-to-understand, but not patronizing. In short, it never felt like a chore reading it. In fact, I rather enjoyed it.
One caveat, it does deal specifically with the Torque Game Engine (TGE), so may be just a little bit dated (though it was published in 2008, so not too old). But if you are using TGEA, the main difference in that is the use of shaders; the TorqueScript language and much of the engine is still the same, so this book is still very useful. Even for T3D, these books are highly recommended, you just need to pay attention to differnces in the code.
Multiplayer Gaming and Engine Coding for the Torque Game Engine shows game programmers how to get the most out of the Torque Game Engine (TGE), which is an inexpensive professional game engine available from GarageGames. This book allows people to make multiplayer games with TGE and also tells them how to improve their games by modifying the engine source code itself. After reading this book and completing the exercises on the accompanying CD, game programmers will be well prepared to make their own complex, exciting games using the Torque Game Engine.