It refuses to provide more than very vague information about how the money was spent in Haiti (information like "35% of $488 million on shelters"), with no specific details about what projects they spent the money on, how those projects went etc.
When the author challenged the general counsel of the Red Cross to provide more detailed information ("because clearly you must have it") he just gave her some evasive boilerplate spiel about having provided the summary information he'd provided already.
How can anyone donate to a charity that's so stunningly opaque about how it spends its money?