I am a big meatball sandwich fan, and not all of them are created equal -- that's for sure. In fact, I just ate one a few days ago at a place in the Original Farmers Market and, while it tasted great, there was so much cheese and not enough meatballs! Subway's meatball sub doesn't taste like Jersey Mike's, nor does it taste like Quiznos', nor does it taste like Which Wich's, nor does it taste like a big, hearty sub you'd get at an authentic Italian restaurant.
Earl of Sandwich had a meatball sandwich that didn't taste like any other chain's meatball sub either -- there was something unique about the sauce. It was a bit tangy, I guess? And it had mozzarella and parmesan on it. Just a really good flavor. I am forlorn that they won't make it year-round. If they can have a holiday sandwich all year long, a meatball sandwich shouldn't be that difficult to make.