calm down dude...there are two essays...one for additional comments, one for diversity. i'm not putting anything in the first one.
Sorry, I didn't mean to come off as mean or anything. When he said additional comments I thought he just meant the open boxes if you say Yes to any questions. My mistake and I completely apologize.
I think cdonahue put it best in saying that you simply have to be honest. If you truly have nothing to say then don't say anything. Basically, don't try and fill up space. But if there is something you would like to add, it doesn't hurt and it most definitely will help - expertise in a field of art, music, playing a college sport or something. And why not help your application out?
I do still think that the essays are meant for the school to get a better idea of you and for you to stand out more. With the school receiving close to 9,000 applicants a year, it's definitely helpful if you have something that helps them see you in a different light or makes a lasting impression on them. Maybe you wrote everything you needed to in your AMCAS and maybe you have things you wouldn't necessarily have room to or want to put into your primary. Either way it's a case by case situation. anyways, good luck and sorry again for the miscommunication earlier.
If it were worded like Boston's Secondary where they really seem to emphasize NOT writing anything extra unless it's super extraordinary then I may feel differently.
I have to say this though, if two borderline interview applications were received and were identical in stats and activities, that additional comments box *could* make or break the decision. If it was written simply to fill up space and was complete BS, then it would break it. If it helped the committee see the applicant's other qualities (commitment to service, research, maybe extended experience in a field that would contribute to the diversity of the class) then it may make it. Do I necessarily agree with this? I'm not so sure playing piano for 15 years makes you a great medical doctor. But it is what it is and just like in undergrad when you had to do well in school, volunteer constantly and gain healthcare experience, the application is another hurdle to jump.