I finished reading his biography just a few days ago....
When his daughter lived in DC, she couldn't afford a new television. It took pleadings from one of Buffet's old friends, the former owner of the Washington Post, before he sprang for the new TV(he was worth only a couple hundred million at the time, but, then again, TVs were cheaper too). All the while she lived in a tiny apartment, with barely enough room to sit down in the kitchen.
For years now, he's been telling his children not to expect a dime. In his later years, he relented and said he'd give thim something (at the time of publication, I believe it was somewhere in the neighborhood of 3 million each).
A billion to each heir sounds extremely out of character. Either he's starting to lose it, or he's stopped caring. This is a man who still lives in the same home he purchased in 1956 for $31,000. A man who thought that a corporate jet was the biggest, most indulgent excess of big business (although he lived to greatly enjoy this). He's a guy who knows the value of a dollar better than anyone, even those who don't have that dollar. To him, it was never: 'what can a buck get me today', it was: 'what can that buck grow into over 20 years.'
I applaud his contributions. So what if he lived to be 75 before giving significant portions of his massive fortune away. He's still doing it, and in doing so, will make a million times more of a difference than the average detractor that sits and whines about how criminal it is for a single man to amass so much.