I'm happy with the Obama win in Iowa for the following reasons:
1. His policy proposals are, for the most part, intelligent and based on actual research and data on what works, and he talks about them in a way which gets people excited and often persuades people who didn't agree with him in the first place. This bodes well for his ability to actually make things happen.
2. He's the biracial child of an immigrant and a midwesterner, with roots in so many different pots that most anyone can look at him and see something that resonates. That bodes well for his electability, his ability to relate to people, and makes him an inspiring figure that helps show the best face of America.
3. Obama's made the claim again and again that he was doing a new kind of politics, that he could bring people not currently politically involved into the system. He's also made the claim that his political organization skills would help him do this within the current system. The caucus process has a high barrier to entry for those kind of people, but Obama clearly pulled it off, more than proving his claims.
In other words, I think Obama is an inspiring figure, I like what he wants to do, and I think he's got the skills to make it happen.