Yeah, that's it, he's just "special" and in a show like LOST where there's all kinds of supernatural occurrences going on anyway (like mediums, the "heart" of the island, Jacob and MiB's powers etc), "special" doesn't necessarily need an explanation as such. However, given that it seemed to be used as a very specific word, and used for other key characters also, I had wondered if it would be brought in to some point in the ending as it was for Locke and Desmond.
That's why I'm not too caught up in conspiracy theories for it. I watched the whole thing and took what I needed to from it. I've seen some people still trying to work stuff out after the finale, as if there's still more to dig in to and reveal, but they're never gonna get answers because it's over. The 'canon' of the show is finished, so anything else that they come up with is only ever going to be guesses and theories, not answers. I thought the final was a nice way to end it all, there could be a few different ways to interpret it (meaning the revelation Jack receives from Christian in the funeral home), but I don't see how any of them dramatically alter the meaning of the whole thing, so it's all good in my mind.
BTW, the final ending shot, ending just as it started, was so epic. I love shit like that.