After googling for many days about features of 4.4 , I don't see any point to upgrade to 4.4 because
# I rarely used google now.
# Write messages occasionaly
# using truecaller ( flawless) for caller ID
# can not get GEL after update
# don't like rooting
# my phone is already giving lightning fast performance
# don't know about others but 100% satisfied with camera
# 100% satisfied with resolution of N4's screen
# I like its curved screen edges
and in the end my greatest fear of upgrading to 4.4 , I don't want to face any unwanted performance issues after upgrade because my phone is out of warranty . Now do you tell me any compeling reason to upgrade to 4.4 ? I mean Please suggest me ,why should I upgrade to 4.4 ? Thanks in advance .
I'm not sure that any of the reasons you list have anything to do with upgrading the version of Android on your phone. Here are my responses to the things you list out:
# I rarely used google now.
Just because you update to 4.4 does not mean that you have to use it more. It's still pretty much the same on then Nexus 4.
# Write messages occasionaly
Not sure what this is referring to, but the amount of messages you write should not be tied to the version of Android you are running.
# using truecaller ( flawless) for caller ID
You should still be able to use this app with 4.4 unless it's not supported on 4.4. I know the OS will do this for you automatically, so you may find that you no longer need the app.
# can not get GEL after update
I'm not sure what GEL is so I cannot comment on this.
# don't like rooting
You only need to root if you want to install the factory image now. The OTA update should be released in the next few days and does not require rooting.
# my phone is already giving lightning fast performance
Noting in the new version of Android should impact this in any way. From what I can tell the new version will utilize less memory, thus resulting in better performance.
# don't know about others but 100% satisfied with camera
Your camera and resulting pictures should remain as they are now. There will be a few new camera features but this should not impact your pictures in any way.
# 100% satisfied with resolution of N4's screen
Screen resolution is determined by the display in the device (HW) not by the version of Android that you are running (SW). Thus, this will not change as a result of the 4.4 update.
# I like its curved screen edges
Again, you are not updating the HW, so the curves screen edges will remain curved. Are you thinking that after you update to 4.4 that your Nexus 4 turns into a Nexus 5??
Your final point is that you are concerned with performance issues. I think that Google has likely testes 4.4 on the Nexus 4 and has come to the conclusions that it must be an improvement over the 4.3, otherwise it would be a bad decision on their part to push it out to users on a mass scale. Others have highlighted how the memory management is improved and how this has made a slight, but noticeable difference in speed on the device.
I think the biggest thing to worry about is app compatibility, but this falls more on the app developers to make sure their app work correctly on the new OS. So, unless there is a particular app that you use on the regular that you know will not be supported on 4.4, then I don't think you have much to worry about. If you want it play it safe, then just hold off for a few weeks and monitor the forums for issues before you make the plunge. I'm not personally excited about this update, but if the end result is a faster OS then I'm more that willing to give it a spin. OS updates are rarely a step backwards (unless you're talking about IOS 7 or Windows 8!).