For my Nokia Lumia 925, I got the updates about a week or so back. I got both Nokia Lumia Black firmware upgrade and Windows Phone OS GDR3, I didn’t notice at that time these two were different, so I don’t remember whether both came together or I got GDR3 (aka Update 3) sometime earlier.
The Nokia Lumia Black Firmware update (WPcentral article) is about improvements to Glance Screen (which I never had any complaints), camera and Bluetooth 4.0 LE.
I found the GDR3 to be more interesting, this adds Driving mode (a welcome feature), screen orientation lock (I wish there was a quick access to this through a button), App switcher improvements, custom ringtones and Wi-Fi during setup (an annoyance in WP before this).
The new Zune browser is surprisingly good, but not as good as the iPod’s. It works well, but isn’t as fast as Safari, and has a clunkier interface. If you occasionally plan on using the web browser that’s not an issue, but if you’re planning to browse the web alot from your PMP then the iPod’s larger screen and better browser may be important.