Nothing is good or bad, so the question doesn't make sense.
Now if you are asking whether porn has a positive or negative impact, or if it's moral, or if it's ethical, or if it's widely accepted, then you could get a concrete answer.
I'll answer the impact one, I like discussing impact.
The impact of porn can be positive or negative. On one hand you have people who exploit people or take advantage of people's carnal desires in order to make a few bucks.
On the other side though, you can have open and willing people who are exploring their sexuality and choosing to share it with the world. Nothing wrong with that at all.
It all depends on how you look at it, and what you believe in. Porn, just like *anything* else, isn't inherently good or bad.