Because I should be bed by now. I'll write my shorter two cents. XP

Yes. Personally I can judge good RP's vs bad RP's, to things I've been in personally, or to just looking at them without context. Though the factors of what make them good differ drastically if it's something I'm personally apart of or not. It's just a different form of writing, it can be artful, fun, or terrible depending on all the pieces involved. And it actually has more factors than just how the writing is. I've been in RP's were the writing was fine and the plot moved fast enough, it probably would be remotely enjoyable to read. But the way people got along, and how certain actions transpired, I wouldn't call it a 'Good' RP.

* I believe not all that is done is automatically art. But some can very well be, yes.
* Don't understand. I suppose my question, is a book less artful than a movie? I know opinions would be far different depending on who you asked. Those people that believe the book is always better than the movie. I mean most screen plays or movie scripts are technically written by more than one person. I know some people edit RP's they do and make them into books. I think it's the writing equivalent of gaming. It's more of an interactive medium. Can games be art? Are they less art than movies?
* I mean it can be personal, and usually is, but not everything is an opinion. Yes something's CAN be better by fact. Games for instance, smooth and high frame rate is something that cannot be argued. For role playing, writing capabilities of the group would probably be a noticeable factor.
* I suppose it's good to finish something before you judge it critically. And good RP's do know how to end, and usually do have an ending point set in their heads.
* Well not all RP's on websites have this exact thing, so this is specific for this site. But I will say, good role players. (vs good RP's help.) Do matter in making an RP a good experience. So people who can write just fine, but are incredible inactive or slow or rude or bitchy about unimportant details. A good RP it doesn't make. I don't think writing more/advanced automatically equals better. If that's the question. Since RP's are suppose to be interactive, overly long posts can make your pacing drag on tremendously. I'd call it the equivalent of having cut scenes in your game. Some is fine, but too much ruins the whole interactive thing.