I have read many good investment related books, but I have to say that "The Warren Buffett way" had a huge impact on my thinking when I read in the aftermath of Internet bubble bursting. I'm currently reading "The Snowball: Warren Buffett and the Business of Life", which seems even better as it goes deeper into life and methods of the worlds greatest capital accumulator.
To get idea of investment/management philosophy of Warren Buffett, you do not necessarily need any book as the core ideas can be read free from the web. You just need to put the pieces together.
- Annual letters to Berkshire Hathaway shareholders
- Owner's manual for Berkshire Hathaway
To understand Buffett's stellar performance, you have to understand concepts such as "insurance float".