
Here comes a very happy news for the iPhone 4S users. The device released on 2011 will be getting iOS 9 update.
Apple confirms that the following devices will get the iOS 9 update

iPhone 6
iPhone 6 Plus
iPhone 5s
iPhone 5
iPhone 5c
iPhone 4s
iPad Air 2
iPad Air
iPad 4
iPad 3
iPad 2
iPad mini 3
iPad mini 2
iPad mini
iPod touch fifth-gen
You need to have just 1.3GB of free space to download and install the update (the space requirement for the earlier version iOS8 was 4.6 GB).
iPhone 4S is available for around INR 14K. When comparing to the Android devices no phone is supported with the operating system update this far, that 4 years of support from apple for this device.
iOS 9 Features
Better battery life
smaller update compared to previous version
Faster and more responsive
Better security
Move iOS application to migrate from Android (transfers your contacts, message history, camera photos and videos, web bookmarks, mail accounts, calendars, wallpaper, and DRM-free songs and books)
Apple have not yet announced the release date of the iOS 9, it is expected later this year.
Read more about iOS 9 - here