The descriptions of units are worthless, virtually the same as in the manual. Very obvious points are made about unit abilities, mostly a rehash of info in the manual. Several facts are simply wrong. There is a ton of historical info on the real-world counterparts of all the game units.
That's nice, but it would be much better to have some meaningful detail on how they work IN GAME.
The walkthrough is OK if you suck at the campaign. It takes up way too much space.
Multiplayer is where this game is at, and it gets a very thin few pages. No useful advice is given on unit counters or strategies or matchups. Each multiplayer map is described only in the most general of terms, with virtually no useful info, just a few generic remarks. "This map is a Sniper's heaven." OK, why? Should I spam Snipers and win? Why not?
DO NOT buy this book if you play RTS games a lot. Don't buy it if your focus is on multiplayer. There are better resources online, far better.
You may consider buying this book if you are only a very casual RTS gamer who doesn't care about multiplayer and has $20 to blow.