The new logo has been designed, wrote Sean Martell, Mozilla's lead visual designer, with "SVG compatibility and color consistency" in mind. It doesn't ditch detail just for the sake of it, he said in his blog post about the change, but actually adds more detail in some areas.
One major detail he pointed out that has changed is the fox's arm. It now comes from its shoulder, instead of the middle of its chest like a disjointed orange tongue.
The updated location bar now automatically hides when not in use, to free up precious mobile screen real estate. To make it reappear, swipe down from the top of the screen. The bar, which Mozilla refers to as the "Awesome Bar," includes domain autocomplete for finishing URLs for you as you type. The company says that its the only mobile browser on the market with that feature.
The mobile browser now supports adding RSS feeds directly to My Yahoo or Google Reader, although that's going to have to change soon as Google Reader is shutting down July 1. You can add a feed to your RSS reader by long-pressing on the location bar when visiting a site.
Firefox for desktops' Switch to Tab feature is now available in the beta, too, so you don't have to open duplicate tabs to get to one that's already open. You can also change the default search engine provider in the mobile browser by going to the add-ons manager and long-pressing on an installed search engine.
The full changelog for Firefox for Android 23 beta is available here.