I did the SAE course a few years back and am happily freelancing in the post world. If ARTI is anything like SAE, you will get out of it what you put in to it.
If you are the type of student that likes to be led, you won't get very far. If you are pro-active, do allot of your own research and set your alarm clock every morning to be the first to call the school to check if there are any cancelled studio bookings that you can snatch up, you can learn allot.
Another very important factor is the quality of the individual teachers. Unfortunately that is hard to tell before you attend the school. You could get lucky or... unlucky.
I believe my SAE degree has only contributed to a small degree to my success as a freelancer. Determination, work ethics, determination, communication and social skills, determination, technical abilities, determination, a nice (pre audio career) CV, determination, flexibility, determination, a good ear, determination, attention to detail and determination had more influence. I think that determination is also quite important.
Did I mention determination?
Alistair