I have two bits of advice for people that classify Obama as an empty shirt. Check out his website and read his book.
Here's an overview of his issues, each link has items of legislation he's written and/or sponsored:
http://www.barackobama.com/issues/
He has not yet gotten deep into policy in his rhetoric yet... because policy doesn't make for good rhetoric. Give him time.
For those that say he lacks experience, I ask you this: how does 24 years in the Senate prepare you to be president? How does being a governor? The demands of the presidency far outstrip any other office. The only candidates with real applicable experience for the job are Hillary Clinton, who lived in the White House for eight years and was an incredibly active First Lady, and Bill Richardson who was a cabinet secretary, congressman, and is currently a governor.
I'm not saying that experience isn't important, just that it's not the be all end all... especially for a legislator who, as time goes by, accrues politically damning votes like my cousin collects the tabs of aluminum cans (don't ask). Obama has ten years of experience in the legislature (8 State, 2 Federal). That's more in years than Romney (four years as Governor of Massachusets) and Giuliani (eight years as mayor of NYC). Don't expect the experience card to be played too heavily if they get the GOP nomination. Edwards has six years in the Senate and, unlike Obama, that number isn't going up.
Most importantly, don't count any one out as unelectable. If you like any one as a candidate, but can't support them because you think they're unelectable, we're just going to end up with another milquetoast candidate. At this point four years ago, Bush looked untouchable. Before Katrina and before the war dragged on and on it seemed incredibly unlikely any one would be able to unseat him. And then things started slipping away... but by that time the Democratic Party had nominated Kerry. Not an inspiring choice, but he was deemed more electable than the polarizing Dean.
Well... Obama is inspiring. And he's not polarizing unless you can't look past his skin color. Rather than bemoan the fact that he can't get elected, I'm going to go out and see if I can change that.