The Benghazi, Libya attack is certainly out of the ordinary. For one thing, it's received a lot of media attention. For another, it's sparked a kind of arbitrary and wholly unnecessary witch-hunt in Washington as Republicans seek a way to blame Democrats and the POTUS for the fact that four Americans were killed.
But the attack in Benghazi was not in and of itself unique. It wasn't the deadliest, wasn't the most coordinated, and possibly not even the largest attack that our foreign embassies have endured in recent years. In fact, here's a list of attacks that were just as deadly, if not more so, from the previous administration.
What makes Benghazi unique? The fact that we lost an ambassador? Yes. The fact that it occurred under a Democratic President? Sure. But do those factors make it worse than the attacks listed in the linked article? Not in my opinion.
Oh, and as an aside, keep in mind that 9/11 happened under Bush's watch as well. He was briefed on the attack several times in the weeks and months leading up to it, and did nothing. He was told about it the morning it happened, and didn't act for over an hour. Now, was that a failure of our intelligence community, or our leadership? Sure, but no one ever seems to point that out anymore.