Here's a good article defending Dean from conservative columninst Andrew Sullivan in Time:

an excerpt:

Dean offers, to purloin a phrase, a choice, not an echo. His pugnacity in defense of his liberal instincts is obviously genuine. After eight years of careful Clintonian positioning, it's refreshing. Compared with Kerry's packaged, tested, hollow rants against "special interests," Dean's straight talk is invigorating. He isn't haunted, as Kerry is, by the specter of Vietnam. Even the famous Iowa scream had more authenticity and fire than Kerry's labored recitation "Bring it on." Unlike Kerry, Dean has held a serious executive office — balancing budgets, reforming health care, innovating on civil rights. Kerry's undistinguished, flip-floppy Senate record is far less impressive.

Is Dean too extreme? On the critical matter of national security, Dean has a more defensible record than Kerry. He backed the first Gulf War, which Kerry couldn't bring himself to do, and the Afghanistan war. His opposition to the Iraq campaign is less a function of knee-jerk isolationism or even left-wing pacifism than a pragmatic judgment about how to fight best. No, alas, he's no Joe Lieberman in the war on terrorism. But his character suggests far more backbone in foreign affairs than does Kerry's Hamlet-like anguish and spin. I don't see Dean as President caving in to Jacques Chirac. And Dean could also save the Democrats from a left-wing split. In 2000 Al Gore lost in part because of the far-left Ralph Nader challenge. Dean has managed to bring these voters back into the fold — without making any drastic policy commitments that could come back to haunt him. Kerry in comparison? Gore redux.

(...)

Would Dean nonetheless be buried in November? Maybe. But maybe not. Bush is vulnerable in many ways — on fiscal negligence, unseen problems in Iraq, corporate coziness. And Dean is a conviction politician. Like Margaret Thatcher, he may command the respect even of those who disagree with him. He once told the New Yorker, "I think the problem with the Democratic Party in general is that they've been so afraid to lose they're willing to say whatever it takes to win. And once you're willing to say whatever it takes to win, you lose." That's a brilliant analysis of what ails the Democrats — and it's why, even under Clinton, they saw their congressional power ebb and collapse. If Dean is a doctor, he's got the diagnosis dead right.