It's in the "a" where LDS parts theologically from Protestants and Catholics. That and we humans becoming new gods.
I wouldn't vote against someone just because they're LDS, but I think Romney tries here, like many LDS, to diffuse the differences - they are quite stark in actuality.
He does admit to differences, albeit in very broad terms:
"My church’s beliefs about Christ may not all be the same as those of other faiths."
I think he should have been more explict that those differences are large, without getting into any details. In fact, I suggested to his staff that he say something like this:
"I recognize that my church has some fundamental theological differences with other Christian Churches, and that these differences are so large that some churches don't even consider my church to be Christian. That's okay. This is America and they're entitled to their opinion, and I don't see it as my job to change it. I'm not a spokesman for my church. However, I don't beleive these theological differences are relevant to the office of the president. I'm running for commander in chief, not pastor in chief."
But on the whole I think it was a good speech.