For certain consumers, it might be a good thing in the short term. Imagine your grandma only has internet to check facebook to catch up with family news, and does nothing else. She might be paying $50 a month for that. Hell, maybe she'd like to be on facebook but can't justify the cost of the internet just for that.

In comes not-net-neutrality. The ISP offers a plan for $20 that can only access facebook. It's cheaper to provide for the ISP as facebook isn't going to use as much data as something like netflix. But also, facebook can pay to subsidise this as facebook make their money back by getting more people on facebook to see ads, having grandma tell her friends and also join facebook, and by having it infeasible for people to use other social networks (bebo isn't paying so if people want to use it they have to pay the full rate - therefore facebook can hold and increase their monopoly).

This already happens in other countries, and I hate it. It stifles competition and means new startups (like facebook was once) would not be able to survive.