What constitutes a "good" Philly cheese steak sandwich?

[Hoff]

I'm just curious, as I really like this sandwich and every place does it a little different, but I always end up enjoying them. This is likely due to my general love of food and more particular love of steak, peppers, and onions. But I mean, I've heard people from the northeast talk about a "real" Philly cheese steak, and I have no idea what that means. Is it something in the preparation? The presentation? Je suis confondu. Help a brotha out, if you have any info.