I got into the menu and noticed it is "Hardware Version 2." Now if only I knew whether my old one was Ver. 1 or not!
I'd say the more solid construction seems to make the phone feel heavier, or at the very least, less "hollow" as you described.
As for the battery, I always have enough to make it 1-2 days so I am fine with the battery life. I have to charge this phone as often as I have had to charge any other, yet it does so much more.