Samsung Galaxy SII Jelly Bean (Android 4.1.2) Update Is Rolling Out In India
The most obvious, expected and noticeable improvement is in the performance of the phone. The firmware will make the phone more stable (thanks to project butter) and give a refreshing new look to the GUI (similar to what you see in the latest phone in the Galaxy series). The Jelly Bean would also bring features like Direct Call (just move your phone near your phone and the phone will dial a call to the contact that was on the screen), Smart Stay (phone stays on when you're looking at it, the screen doesn't go blank), Pop-Up Play (allows you to pop-out video player and put it anywhere on the screen).

Other exciting features include dual home screen modes, an improved notifications system and more options to the buttons in the notification bar. The upgrade also packs Google Now, TouchWiz Nature, S-Cloud services and brings a few more features to camera. Of course, you won't miss out on a new lock screen.
What we're hearing from different sources is that the Samsung Social Hub has been removed because it's not compatible with the SII's hardware. This includes instant email & message notifications. Other apps which you might need like Polaris Office and Photo Editor are available for separate download from Samsung Apps center.
The update is being rolled out OTA aka Over The Air. We'd recommend hooking your phone to the nearest, trusted wireless signal update the firmware. If you choose your data plan to download, then you are likely to incur data charges. Those who're new to the upgrade process may note that OTA update is available through your phone's settings -> About > Software Update.
Other method to update the phone would be through Samsung Kies. Get the latest copy of the Kies software from Samsung's official website and install it on your computer. Plug-in your phone via USB and Kies will notify you that a new firmware version is available. Start the upgrade process and be aware that it may take several minutes before the firmware is downloaded and installed on the phone.
Don't forget backups: It's strongly recommended that you should backup all your phone's data because if the upgrade fails, there are high chances that you might end up losing your contacts, music, files, videos and apps. Use the Kies software that offers a very simple backup process for your phone.
Finally, we'd like to thank Samsung on behalf of all the Samsung SII owners. You kept your word of not ignoring the earlier models as you keep launching the next wave of phones.