The only thing you can possibly fault the administration for is deliberately downplaying the Al Quaeda connection. This is not new information - back in November, Former Director Petraeus
said as much. He said it was an attempt to avoid tipping off the groups they were tracking. If true, it wasn't very effective, but I'm not seeing any contradictory evidence or a better explanation at the moment.
There were some legitimate complaints about how light the security was, too. However, the complaints about that seem to have stopped after the Republicans realized they were the ones who voted for the security cuts.
There is not, and never has been, any evidence of misconduct during the event itself. Not that anyone seems to care about evidence.