In this book, Robert Hagstrom discusses the power of focusing one's portfolio. On the oft-discussed eggs/basket spectrum, Hagstrom comes down squarely on the side of "put all your eggs in one basket, and watch that basket". It's what is preached by Buffett and Munger for those who know what they're doing. Unfortunately, I'm not sure it's that easy to tell if one knows what he's doing. At any one time, a large chunk of investors will be outperforming the market over some arbitrary period, and because of human nature they will be oozing with overconfidence. Should all of these people be focusing their portfolio to take advantage of the gains in their best ideas? I'm not so sure! I've been at this for several years myself, and I must say that only recently am I starting to feel like my favourite ideas are outperforming my less favourite ones...and that could just be by fluke!
But the book is not just about focus. It delves into the multidisciplinary models that Munger is so famous for espousing. As such, it touches on a number of topics mainstream investors probably don't consider, including psychology.
If you're a Buffettphile like me, there probably isn't that much to gain from this book. After all, it is based on secondary research that you've probably already read/seen/heard. But for beginners, it's a decent place to continue to learn about investing (as long as you don't start 'focusing' right away!).