Well, I think her weaknesses aren't secrets or anything. She is a centrist, her public persona can come across as wooden and patronizing (though not always), she represents establishment and dynasty in politics, she has some foreign policy baggage, and she probably doesn't have as much energy for campaigning as she did in previous races.
Even with all these possible weaknesses, I think the only real hurdle will be the nomination battle, depending on who else runs. If she is nominated, I think she will win. Her support among women, Latino voters and African-American voters will be massive.
I'll disagree on the idea the primary will be tougher than the general.
There may not be any clear alternative to her in the primary. There will be a Republican nominee in the General Election.
Yeah, as we all know, Hillary Clinton has been out of the public eye since her high profile victory over Rick Lazio. That's really going to hurt her in 2016...
Being in the public eye is different than running in competitive general elections.