The Galaxy S III interface (right) feels cluttered and busy compared to Google's base Android 4.0 UI (left).
In terms of the actual interface, Samsung trades the subdued gray-and-blue design introduced in Ice Cream Sandwich for a far more busily colored alternative. Many of Samsung's UI changes seem to have been made merely for the sake of change and at the expense of the user experience: For example, to create a home screen folder in the stock ICS software, you simply drag one icon onto another; with the Galaxy S III, you have to first drag an icon directly from the app drawer onto a "Create Folder" command at the bottom of the screen, then drag a second icon on top of it. Samsung essentially altered the process to make it more cumbersome and less intuitive.
Samsung packed plenty of bloat into the S III, too, ranging from its usual set of content-purchasing "hubs" to a series of Yahoo News applications. (The carriers have tacked on their share of garbage as well; thankfully, most of it can be disabled and hidden from view.) Even elements like the home screen widgets -- of which Samsung has added several of its own -- are visually random. The net result is an OS that feels cluttered and busy, which is a sharp contrast from the sleek simplicity Google achieved in its base ICS software.
Interface aside, Samsung made some innovative feature additions to the Galaxy S III's operating system -- things that actually do add value to the user experience. One of the most useful additions is something called SmartStay: When enabled, it allows the phone to use the front camera to "see" when you're looking at it and keep the screen from turning off.
Samsung also put power controls into the phone's notification area -- a feature that's handy, even if it could be achieved just as easily via third-party add-ons -- along with an option to display your exact remaining battery percentage at the top of the screen. Samsung's nature theme provides some pleasant visual flourishes, too, such as a rippling water effect that happens when you unlock the phone.
Some other noteworthy feature additions: