Do read this excellent New Yorker article on "a legendary problem and the battle over who solved it". The article is by Sylvia Nasar (author of A beautiful mind, a biography of mathematician and economics Nobel winner John Nash) and David Gruber.
Here are two highly quotable quotes from the article:
Grigory Perelman: “It [the Fields Medal] was completely irrelevant for me. Everybody understood that if the proof [of the Poincaré conjecture] is correct then no other recognition is needed.”
Yuri Burago (Perelman's Ph.D. advisor): "He [Perelman] was not fast. Speed means nothing. Math doesn’t depend on speed. It is about deep.
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Thanks to Swarup for the pointer -- through his comment on an earlier post.