My take on the Prima Strategy Guide is that in some regards it's pretty useless, but it is probably worth the $20 (or whatever they are asking for it).

It does include a very nice 2 page write-up on each provence + there is also an interesting chart which demonstrates the statistical advantages/disadvantages of attacking in various situations (you can find sililar tables for free at Terazawa's Resourse Center).

The long and short of it is that it has almost nothing of value to help players learn multiplayer tips and tricks, but it certainly has merit if you want to do well in the single-player battles and campaigns.