Samsung Galaxy S4 owners will probably getting the highly touted Android 5.0 Lollipop upgrade sometime early 2015, but if you want to get an idea of how it will look like on your device, a preview of a build has been leaked. Although the firmware is based on an earlier code released by Google, it more or less will give you an idea of how Samsung has adapted the Material Design of the major update as well as how the TouchWiz UI has been tweaked for the Lollipop.
Earlier last week, a preview of the Android update was shown on Samsung's current flagship, the Galaxy S5. The TouchWiz launcher has been ported to the S4 as well, including the My Magazines feature and the Popping Colours lockscreen effect. What is also obvious with the Lollipop on the Galaxy S4 is that its proprietary apps, like the calculator, clock, contacts, messaging, phone, etc, have been overhauled to adhere to the Material Design visual language that Google has been espousing.
Since it's an early test build, there are still a lot of bugs and fixes that Samsung says it is working on. But those who were testing Lollipop on the Galaxy S4 says that this update is more responsive than the previous KitKat and that memory management has vastly improved. Google released the final Lollipop code base just a few days ago, and so what we're seeing in the preview will vastly improve even more once this final build has been applied.
Samsung has promised that Android 5.0 Lollipop will be rolled out to its Galaxy S5 users sometime before the year ends. The Galaxy S4 owners will have to be a little more patient, as they will probably take a backseat to the current flagship, but based on the preview, it looks like it will mostly look the same for both Samsung devices, at least visually.