Frankly -- I think it's a great source of ideas. My husband has certainly never complained about what I do with the knowledge.
That said, I believe that (like just about everything), pornography can be misused, and it can be detrimental to a relationship if one person has a problem with it. In addition, if someone is indulging in porn instead of tending to the emotional and physical needs of their partner, then there's a problem with it. As I mention in this hub:
...every relationship has different definitions of what is and is not acceptable.