I'd say it's not a form of art, no.
Art implies you engage with something on an emotional or spiritual level, there's some kind of intelligent thought process behind how it was designed or created to stimulate an intense emotional reaction.
Pornography on the other hand is not about any emotional enlightenment or communication, just the gratification of sexual desire, usually in a cliched and tacky way. Sexual desire is not really an emotion in my book, just a biological imperative that kicks in every now and then.
A naked person draped in a pose that suggests some kind of comparison with the force of nature or another meaning or something like that is art to me. A person showing their genitalia for the sake of it and flashing a vulgar grin is not by a long shot.
I think overall porn is kind of unhealthy. As others have said, it fuels unrealistic expectations in partners, encourages shallow thinking and often comes across as rather degrading as a whole.
Nonetheless, as morally contradictory as it sounds, I have used the milder side of it in the past as a way to banish the most unsophisticated elements of loneliness, though I take no joy in using it. In fact, I see it as one of my most negative character traits, but unfortunately I can't totally turn off my human side until I find someone I want. I honestly wish I could
I know for a fact that if/when I ever get a girlfriend, I will stop that completely.
I don't think it's right to view that kind of stuff if you have a partner, while it's not cheating outright, it's sort of acting as though they're not satisfying you.
Long story short: no, it's not art and it's not morally pretty either in my view, but it does serve some discernible purpose for the lonely and single. Those who are married and have loyal partners don't really have an excuse for using it though.