I didn't get into Oxford, but from my experience of applying and from observing the people I know who've got in, I've realised that there is very little difference between those who applied and were rejected (and will now go to other very good top 10 unis) and those who were given an offer other than the fact that the latter tend to be more diligent and efficient when it comes to work and exams. Often, you don't get in because you weren't the sort of person who they thought would best benefit from the style of teaching and atmosphere that is part and parcel of an Oxbridge education. In fact some of the people who got in from my school are shallower and more exam-orientated than those who didn't get in (who are in many cases more intelligent and curious about their subject).
Of the 5 people who applied for History (of whom I was one), 2 got offers. They are also the only two who haven't read any books about their historical interests since the interview. Furthermore, they coincidentally have the poorest written and oral expression of the 5 of us and are the least widely read. But they are also coincidentally the most efficient at exams and, although this was not borne out in their AS results, somehow, this skill must have been noticed by the admissions tutors.
I give this example not, by any means, to denigrate those who got in to Oxbridge nor those who are already there. They are, on the whole, exceptionally good. My point is that they are most certainly not 'special'. In a few cases they are less intellectually able than those who are rejected. There are many exceptionally smart people at my school who freakishly didn't get in. One English applicant springs to mind. If I had to put my money on the most likely humanities student to get a place, it would have been him, and yet he was pooled and rejected by Cambridge. He's now going to Durham, and he will always be more intelligent than many of the people who are going to Oxbridge. I know that if I was an employer and I had to pick between him and one of the history offer-holders I mentioned earlier, I know who I'd choose.
Students at Oxbridge are, on the whole, no more intelligent than those going to other top 10 unis; they just don't have (or appear to exhibit) the right work ethic for the Oxbridge environment.