Android Lollipop brought a great many things to many users, and Samsung device owners are among those users. Aside from bringing in loads of changes like lockscreen notifications, heads up notifications, more vibrant use of colors, and for Galaxy S5 and Galaxy S4 users, a little less bloat and a lighter feeling TouchWiz, it also took one very popular feature away. The silent mode. The good news for those on the Samsung Galaxy S5 is that Samsung brought silent mode back with an update back in February, which also came along with KNOX version 2.0, improving the overall security of KNOX. Now, users with the Samsung Galaxy S4 I9500 seem to be getting the same update, however, it only seems to be rolling out in India at this time.
Keep in mind this is not the initial Lollipop update bringing the Galaxy S4 I9500 forward to Lollipop 5.0, as that has already happened. Rather it's a smaller update that re-introduces the silent mode and KNOX 2.0 just like with the Galaxy S5 last month. Since this is an India only roll out for the time being, (according to the source) it's unclear how long it might take for other variants of the Galaxy S4 in other regions to get this same update. For those already receiving it in India and for users in other regions who will get it at a later point, the update package weighs in at 327MB, so make sure to have a little bit of extra room to cover the storage for the update files. It's also good practice to make sure that you have a decent amount of battery life so your phone doesn't shut down in the middle of the update.
Those two changes above seem to be the only noticeable differences, although updates usually always come with some performance improvements and bug fixes, so those are likely part of the software update being rolled out to users. When other variants of the Galaxy S4 begin to see this update hit their devices, we'll be sure to update you so you can watch for it to come in.