As someone a lot closer to 1300 than IM pfren, I'd advise against Silman's middlegame books.
While his writing is accessable, frankly how to use the information he presents just wasn't clear to me at all. I got a lot more milage out of Yusopov's "Build, Boost, Evolve" series.
But a big problem with Amateur's mind is actually that his analysis of some of the positions are counter against what the computer will tell you about the same position. And it becomes clear that while one way of playing the position might be to follow his advice, there are equally good ways of playing the position that ignore his advice or even run counter to it.
If you just read the book superficially, you might get quite a lot out of it. But if you really try to tackle the positions yourself, you'll find that he hasn't always choosen the best example positions to work with.
neither does those machines players think so highly of.....
Nice review - thanks for taking the time to write that. Given your impressions, for what rating range would you say the book is most helpful?
I'm rated around 1300-1400 right now, and I thought it was about right for this level. I agree with the other poster that its probably more important to understand tactics at this level though. I have read a few tactics books ("Winning Chess Tactics" by Seirawan, "Back to Basics: Tactics" by Heisman and "Chess Tactics for Champions" by Polgar). The outcomes of my games are still usually determined by a tactic or failure to see a tactic.
That said, this book was useful, becuase what do you do when no tactic is available? Silman's book will give you some ideas on making better positional moves.