Maybe it's the way he flung himself into life. He had a dreadful childhood - a mother who wasn't fit to care for a kitten, and sexually promiscuous, as well, a father who went mad, due to the progression of syphilis he'd contracted in a mispent youth, and a poor school record (he was considered not very bright at school). He didn't whine about the unfairness of life, he just picked himself up and tackled life with a will to win. Although he trained as a soldier, his record on the battlefield is more remarkable during the years he acted as a war correspondent (he was captured during the Boer War, and escaped). He was right in the thick of things during that war, and, after, stood for Parliament. He was heavily involved in government and politics for the remainder of his life.
There is much to criticize in his life. As First Lord of the Admiralty in WWI, he engineered the disastrous Gallipoli landings that took so many lives of Englishmen and Australians. He made blunders in setting economic policy, and his post-war management was questionable.
But he could be forgiven much for the remarkable performance in WWII. His influence, I believe, was pivotal in determining the ourcome of the war. His writing is pure Winnie - when you read "The Hinge of Fate", you can hear the cadence of his voice. I've been slowly working my way through his 5-volume war books (the prize from Goodwill scavenging).
Winnie was something you seldom see in politics, but respect when you do - a man of principle. He could be wily, but he concocted his little tricks for an ultimate goal that was worthy.
To finish on a WC quote from Neo-neocon:
"Still, if you will not fight for the right when you can easily win without bloodshed, and still yet if you will not fight when your victory will be sure and not so costly, you may come to the moment when you will have to fight with all the odds against you, and only a precarious chance for survival. - There may be a worse case. You may have to fight when there is no chance of victory, because it is better to perish than to live as slaves."