There’s not much more that needs to be said about the first presidental debate.
McCain was stiff and boring. His framing was awful: he and Obama both said essentially the same thing on a number of issues but the reaction meter consistently showed that people reacted more positively to Obama than McCain. Post-debate polls show Americans thought Obama won and that they trusted him over McCain by large margins on Iraq and, crucially, on the economy.
But, most importantly, McCain did not present real solutions, just tinkering with the same failed right-wing tools. He was rooted in the past and kept referring to obscure parts of his record in the Senate. Obama presented positive, practical left-wing policies directed at better America, and the people loved it.