[Lauren]

Omg, I knew one of them died but I was hoping it wasn't Hannah

I actually think they're presenting the issue in a realistic light (bar the "wanting to be a model" form of anorexia). I think it's important to shed light on the issue to teenagers who may think it's just a 'get slim quick' way of dieting. They do it in a very responsible way because most of the time dedicated to it, is dedicated to showing the negative effects of it.
Had they shown Hannah getting slim, being happy, and being a successful model - then that would have been irresponsible of them, and would be presenting anorexia as a positive thing to do. However, they show her being sick, looking faint, fainting, passing out, looking gaunt, losing friends - quite realistic for how anorexia can affect people.