I wrote this quoting Warren Buffet 10 years ago (in the first iteration of my blog, fascinating to note what has stood the test of time or not):

"A truly great business must have an enduring “moat” that protects excellent returns on invested capital. The dynamics of capitalism guarantee that competitors will repeatedly assault any business “castle” that is earning high returns. Therefore a formidable barrier such as a company’s being the low-cost producer (GEICO, Costco) or possessing a powerful world-wide brand (Coca-Cola, Gillette, American Express) is essential for sustained success. Business history is filled with “Roman Candles,” companies whose moats proved illusory and were soon crossed." 

What he wrote in 2007 in his investor letter, still seems true today. 

Charlie [Munger] and I [Warrren Buffett] look for companies that have a) a business we understand; b) favorable long-term economics; c) able and trustworthy management; and d) a sensible price tag. We like to buy the whole business or, if management is our partner, at least 80%. When control-type purchases of quality aren’t available, though, we are also happy to simply buy small portions of great businesses by way of stock-market purchases. It’s better to have a part interest in the Hope Diamond than to own all of a rhinestone.

Perhaps 10 years is not a long enough passage of time, but it is notable to me that advice given 10 years ago still seems relevant today (and probably 50 years ago as well).

10 years not even long enough to grow an oak tree.

Daniel Loeb of Third Point did criticise Buffet in 2016 suggesting:  Buffett "has a lot of wisdom, but I think we need to be aware of the disconnect between his wisdom and how he behaves."

However, I am always cautious of such lines of arguments.  If a murderer says “Don’t murder” do we not listen to his advice or wisdom because of who he is? While background can give weight or not to the evidence or wisdom (or lack of) said, the wisdom or message itself needs to be evaluated somewhat separately from the person.

If not then maybe we should never read the works of Ezra Pound.

Buffet investor letters here:   http://www.berkshirehathaway.com/letters/letters.html

Some other great nuggets… on customer service:

"The most important development at Berkshire during 2015 was not financial, though it led to better earnings. After a poor performance in 2014, our BNSF railroad dramatically improved its service to customers last year" in the 2015 letter.

This runs through the heart of Amazon as well – relentless focus on customer – serve the customer well and earnings will follow.

On culture…

The 2010 letter quoted Churchill saying, "You shape your houses and then they shape you."

For better or worse, every company has a culture. I’d go so far to say that every family has a culture too.

For better or for worse, you should assess what that culture is.

On valuation…

"As much as Charlie and I talk about intrinsic business value, we cannot tell you precisely what that number is for Berkshire shares (nor, in fact, for any other stock)," 

A company is more than just its numbers… and many things can not be counted, numbers simply can’t properly express value in many situations.