I don't think I've ever had the chance to have one of the first comments before so I just wanted to say that I absolutely love Sexplanations and I'm constantly recommending it to my friends. Keep being fantastic and thanks for all you do to increase public awareness about and appreciation for sexuality! :)
Thought it was great
It's impossible to weigh the pros and cons of most things, porn included. I could easily think of 10 different ways it could affect someone's sex life either negatively or positively. To answer your other two questions, you can have a compulsive behaviour that negatively affects your life, which is what most people would call an addiction. Search wikipedia for Psychological_addiction#Behavioral_addiction to get some more details.