Several headlines have noted Berkshire Hathaway shares are hitting five-year lows. Some think Warren Buffett, Berkshire's billionaire CEO, has lost it. Short seller Doug Kass, for example, says Buffett is guilty of style-drift, i.e., getting outside his "core competencies" as an investor. Recently, Buffett has spent reams of Berkshire's cash, and now he's selling iconic favorites like U.S. Bancorp, Johnson & Johnson, Procter & Gamble, and ConocoPhillips to raise more cash... which he's using to buy bonds of companies like Harley-Davidson and Tiffany's.  That might look un-Buffett to you. And Doug Kass may have been right so far. But I don't buy it. Buffett's style is simply to take as little risk as possible in exchange for an adequate return. That's why he's doing what he's doing. Buffett's recent purchases of $300 million of 15% bonds from Harley-Davidson and $250 million of 10% bonds from Tiffany's aren't style drift. They're typical Buffett moves. Let me explain...  Alice Schroeder, author of The Snowball: Warren Buffett and the Business of Life, tells the story of a private business Buffett once invested in, which made computer punch cards. The way Buffett decided how much to invest took a few minutes. He looked at how much profit the company made and divided that by 15%, and that was the intrinsic value of the business. He bought a stake in the company based on that number.  That's it. That's the core of why Buffett does what he does. He's looking for safety of principal and a satisfactory return, the two conditions Buffett's mentor, Ben Graham, sets out for investments.  In addition to the Harley Davidson and Tiffany deals, Buffet bought $5 billion of Goldman Sachs preferred stock paying 10%, $3 billion of GE preferred paying 10%, $2.6 billion of Swiss Re convertible preferred shares paying 12%, and $150 million of Sealed Air bonds paying 12%.  With the market crashing last year, and remaining highly depressed this year, Buffett once again has opportunities to make 10%-15%. And that's in bonds and preferred stock.  Like bonds, preferred stock is senior to common stock. Bond coupons and preferred dividends are paid out, even if the common shareholder gets no dividend at all. Buffet's a low-risk compounder. That hasn't changed. No style drift here.  Mind you, I'm not a Buffett worshipper. His daffy political views annoy me. For example, he thinks if you steal a certain amount of my wealth before I have a chance to pass it on to my children, they'll be better human beings and the world will be more "fair."  But like many, I admire Buffett's ability to find fantastic long-term investments. I admire his ability to be a relentless compounder of wealth. And I think his recent moves will turn out to be typical Buffett winners. That's why I'm encouraging all of my readers to buy Berkshire Hathaway right now. If Berkshire Hathaway isn't a great deal at this price, then there's no such thing as a great deal.  Berkshire's book value, which Buffett has said roughly tracks Berkshire's intrinsic value, has risen from about $30,000 per share in the middle of 2003 to around $77,500 per share today, a 158% increase. Yet the stock is selling for approximately the same price it sold for then. Absurd.  Berkshire's annual report comes out soon. We'll find out more about Buffett's thinking. In the meantime, I believe Berkshire Hathaway is one of the great long-term investment opportunities of your life. Don't pass it up. Good investing, Dan Ferris  Editor's note: Dan Ferris is a regular contributor to DailyWealth, a free investment newsletter focused on the world's best contrarian opportunities. We write with a simple belief in mind: You don't have to take big risks to make big money with your investments.  Sign up today to read more investment ideas from Dan Ferris.