Excellent answer from Norm Walsh to Jeff Atwood's XML criticism:
I don't necessarily think all the alternatives to XML suck, but the mindless, knee-jerk rejection of XML because it contains a small amount of additional syntax certainly does. Like all tools, it's a question of how you use it. Please think twice before subjecting yourself, your fellow programmers, and your users to more fragile, ASCII-only, ad hoc syntaxes.
This is an occasion where I agree that both alternatives (XML and more light-weight approaches) are worth being considered.