i had an aft balcony once, i believe it was on celebrity constellation but i'm not too sure.
i think aft balconies are bigger, but that might have been just ours because we had a suite. our balcony was the size of my backyard, and i'm not exaggerating. then again, i have a small backyard.
i love aft balconies because you can see both sides of the ship, instead of just one. i also didn't notice any noise or anything like that, it felt and sounded the exact same as a side balcony.