As I remember it when first started getting interest in Bitcoin and looked for an exchange in November '13 the sentiment was unanimous in the community: Mt Gox

As I remember it when first started getting interest in Bitcoin and looked for an exchange in November '13 the sentiment was unanimous in the community: Mt Gox will fail sooner or later, never put money/coins here. But it also looked like a lot of Americans didn't want to hear that because it was the only (as I remember it) exchange where depositing and withdrawing dollars for Americans was convenient. Edit: just saw that other comments say the same thing with more detailed informations, at least it add a data point that even an amateur saw it