Is the very bottom supposed to show the wallpaper too (where the back, home, etc. buttons are) or is that fixed black?
That only happens with on-screen buttons, rather than the capacitive buttons on the Maxx. They will always have a black background.
The look was kept the same as Jellybean (as well as the dialer) at the request of Verizon. I assume to make it easier to support the phone. The list of new features is here:
http://support.verizonwireless.com/dam/support/pdf/system_update/droid-ultra-maxx.pdf
In addition to that:
- there is a new setting for "home" if you have installed a third party launcher to make it easy to set the default launcher.
- there is a setting under "more" under wireless & networks to set the default SMS client
- if you have turned on NFC, there is a "tap and pay" setting that will enable tap and pay with Google Wallet
- there is a bug with the home key that makes a single tap of home act as a double-tap.
- you can now print from apps that support it, and there is a settings->print
- the camera has improvements. If you have tap to focus turned on, there is a new focus/exposure control that you can move around to set the focus point.
That's the main stuff I've noticed. Personally, I don't care about whether the status bar is transparent or black (black probably uses less power anyway), and the network icons are blue or white. Nothing makes one better than the other.