Funny you should post this. I stopped by an ATT store today to try the 1520. I expected it to be awkward in the hand like the Samsung Mega. For whatever reason, the 1520 was *not* awkward to use (at least that's my initial, limited usage impression). I'm not sure what the difference is between them. I wasn't able to compare them directly because the Mega was on the other side of the store. All I know is that when I picked up the Mega a few months ago, I immediately did not like it. That definitely wasn't the case with the 1520.
Regardless, I wish Nokia would standardize on 4.5, 5.0, and 5.5" screens. I don't think the 6.0" 1520 will work in my wife's purse.