They discussed his website on a recent BBC documentary (http://www.bbc.co.uk/programmes/b00nn7vs) at 00:32:37 (transcribed below). The whole documentary is certainly worth watching.
Davis:
"Berkshire Hathaway is a massive company which feels like a family firm.
All the usual corporate vanities are absent and not a cent is wasted. Take a
look at the Berkshire Hathaway website here. To call it low key would be to put it
kindly, it looks though it's from about 1994, no-frills. All the financial data
is here but they haven't even got around to even uploading a photo. And
that's all very much Warren Buffets style - why waste money on a designer.
Buffet insists his website does the job."
Buffet:
"I think it's what we are, I mean, it's factual."
Davis:
"You could put a little picture of something on there perhaps, or."
Buffet:
"I want people to get facts about Berkshire and, you know, I don't
really think it makes any difference what I look like."
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Davis:
"Buffets idiosyncratic style is not just charming, it's a financial asset,
it saves time and money..."