Clinton's guardedness got her overtaken in 2008 by a guy who is, at heart, also calculating, legalistic, and frequently disdainful of his critics. However, Obama also can convey passion and a sense that he genuinely cares about something. He also has a much better developed sense of humor and is a far better speaker (and writer, I imagine).
2016 brings a different set of challenges for Clinton. The anti-establishment mood alone puts a consummately establishment politician like her at a disadvantage, as her continuing struggle for respect among Democrats shows. Bernie is behind in delegates and has no chance of capturing the nomination without a floor fight, but he's the one actually inspiring Democrats. As a rank-and-file voter, I'll support Clinton in the general election (assuming she's the nominee), but I won't be excited about her. I'm a default Democrat, and have been for a while, entirely because the Republican Party stands for a bunch of things that appall, repel, and/or scare me.
Which brings us to Trump.
I won't recapitulate all the reasons Trump's a terrible human being and an even worse candidate for president, because none of that matters as far as Clinton's concerned. The Republican Party establishment itself tried mightily to make these points, and look what happened: if the effort didn't backfire, it sure as hell didn't help, either. There's no reason to believe the Clinton campaign's efforts will be any more successful. Like many of Trump's primary rivals, she's a traditional politician, with a traditional politician's instincts for how the game is played. Trump clobbered such traditional rivals in Republican primaries, and not just because Republican primary voters are in a savagely anti-establishment mood. He has found ways of appealing to people who have been disaffected by both major parties.
Trump has a track record of making insults that stick to his opponents. He also has a near-magical ability to redirect the national conversation when it isn't favorable to him. Clinton needs a campaign advisor with street smarts who can counter these advantages, or she will be a footnote in the history books — just another failed presidential candidate.