Obama has been spun pretty thoroughly. For example, he has worked as an academic, politician, lawyer and community organizer (in descending order of time). The spin is that he is by profession a community organizer, but in reality that was a job he held for a short time early in his career. He worked as a community organizer for three years when he was just out of college, but most of his career (12 years) he was a university lecturer. His credentials as an academic are furthered by the books he has written. However, Americans have a bizarre distrust of "Eastern intellectuals" so the professorial aspect of his life is greatly played down.
The academic side of Obama is one of his great strengths. He appears to have a clarity of thought and ability to contextualize that is quite extraordinary. For this reason I have often appreciated hearing his take on subjects. For example, in the aftermath of Katrina when the media was blaming the government's lack of response almost completely on racism, Obama described the reasons for the negligent response with clarity and precision.
The weakness of Obama's analytical ability is the weakness that affects all aspects of Obama: lack of experience. Bill Clinton had a similar ability to cut through the guff and speak plainly with great wisdom about events, but Bill Clinton always seemed to completely on top of issues (with an uncanncy ability to spout complex statistics), while in many cases Obama seems to be out of his depth.
As many people have noticed, the "real Obama" that is coming through during the campaign is much less liberal than he appeared in the primaries. He seems to be something of a hawk. He turned his back on campaign finance reform. His health care, economic and energy policies are quite a bit to the right of, say, the middle-of-the-road Canadian Liberal party. I'm not sure this is avoidable, though: the US population is so far to the right that it may not be possible to be a true liberal there and stay a contender. And it's not clear whether his rightist views are campaign spin or whether they are sincere: unfortunately, he doesn't have enough of a legislative voting record to indicate where his true policy beliefs lie.
Obama is also emerging as a tough, no-holds-barred kind of politician (what they call "Chicago rules"). It's possible or even probable that every successful US politician has to be a bit of a dirty fighter, but that it's more apparent with Obama because his Kumbaya persona in the primaries suggested that he was something different.
It seems that to many people, Obama's greatest strength is his ability to inspire. This is a tough one for me because I find his style of speech-making to be really annoying. I don't like the preacher tones and fake southern accent, and I don't like the short sound bites ending in a rising note signifying an assumption of wild acceptance. I find his speeches to be trite. To me, this seems to be more a matter of personal taste; but it seems that to people who like his style, it is fundamental to his ability to promote some sort of undefined better world.
There is a bizarre assumption that Hillary Clinton supporters who do not support Obama are not supporting him because they resent the demise of Hillary. This isn't the case with me. I am iffy about Obama now for the same reasons I didn't support him in the primaries: I doubt that he has the experience to be a competent president. I think he'd be a dynamite VP and that eight years in that spot would have made him ready to be a great president. A Hillary-Obama ticket (with Hillary at the top) would have assured the US of 16 years of good governance, but now... I would prefer to not have another Republican president, but I'm not sure that Obama is up to the challenge.
McCain really hit on something in his ad about Obama being the world's biggest celebrity. Obama's impressive interaction with world leaders was mitigated somewhat by the giant European crowds that turned out for his speeches - it made him seem more like Bono than like a US president, more like a phenom.
I'd like to be convinced, but so far I'm not. The kinds of doubts I have may be why Obama, even in the current anti-Republican environment, isn't doing much better than McCain in the polls.