The thing that interests me about photography and why it's different from all other media, is that it's the only medium in which there is even the possibility of an accidental masterpiece. You cannot make an accidental masterpiece if you're a painter or a sculptor. It's just not going to happen. Something will be wrong.
This is simultaneously photography's great advantage and its Achilles' heel: it is the easiest medium in which to be competent. Anybody can be a marginally capable photographer, but it takes a lot of work to learn to become even a competent painter. Now, having said that, I think while photography is the easiest medium in which to be competent, it is probably the hardest one in which to develop an idiosyncratic personal vision. It's the hardest medium in which to separate yourself from all those other people who are doing reasonably good stuff and to find a personal voice, your own vision, and to make something that is truly, memorably yours and not someone else's. A recognized signature style of photography is an incredibly difficult thing to achieve.