Who is in the interior decorating/design field?

I am considering taking up interior design. What can you tell me about this field? I want to know both good and bad. If you are a student,please explain to me your experiences as to whether or not if the studying is hard because I have heard that you have to put in at least 30 hours a week of study time.And I would like to hear the views of people who work in the field. Has it been rewarding or a disappointment,please explain in details. I want only serious responses and only from people who are actually familiar with this trade.