Originally Posted by fffft
Your instincts are dead on. Updates may fix bugs or add a desireable feature. But just as often they introduce new bugs, break root or disable root exploits, break a few apps and add noxious DRM frameworks like the Knox qfuse warranty bit. They can seriously mess up a custom ROM and may depreciate features like MSC or car dock that may be important to you personally.
Updates cannot always be reverted. Try downgrading your Kitkat baseband to Jellybean and see what happens. Or try removing the Knox security bit after you take the update that introduced it. I disable automatic updates and wait to hear what early adopters find before upgrading.
Unfortunately you didn't tell us the all important version of your update. Or even tell us what your current firmware version and carrier are. Your update might be similar to the recent ATT /Verizon OTA adding the mixed blessing of reactivation lock. That is causing bootloops for some people with custom kermels. 4.4.3 is mostly bug fixes, with a few UI tweaks. And I believe 4.4.4 took aim at closing yet another open-SSL exploit and reverting some of the new 4.4.3 bugs.
No matter what an update intends to do, a few new bugs and unexpected conflicts usually turn up. A quick Google finds reports like this:
Thank you very much for your detailed answers! That's exactly it! And I know from experience that updating firmware can cause a negative affect to the phone's performance. My iPhone 4S is still on iOS 5.1 but runs perfectly, while friends who updated their 4S to 7.1 experience freezes and heavy lag. Maybe companies do this deliberately, so people get frustrated and end up having to get the latest, more powerful model so the OS to run smoothly?
I do exactly the same, I always wait to see what people about an update before updating. The only difficulty with Android updates is that there seem to be so many different versions of updates. For example, when I researched the 100mb one for the S5,* various sites mentioned it, but others say the size of the update was 30mb, which were called "improved performance" I also heard about updates not always being able to be reverted to the previous version,* and also about Knox. So, you can see why I'm hesitant to update.
I know quite a bit about using Android, but have very limited knowledge regarding rooting and custom roms and so on. Also, after reading that rooting a phone incorrectly can turn it into a brick, I'm happy to just leave it as it is. I've attached a photo which shows my current firmware version, as well as other information. Also, as my S5 is unlocked, the only updates I'll receive will be from Samsung. I asked my carrier (T-Mobile UK) and that's what they told me. Only phones from bought from them include added apps that they put on, and I think they may also be able to tweak the updates received, by adding their own features.
Some more questions for you;
1. Do you recommend a factory reset after each software update?(I had to factory reset my S3 to stop the battery draining issue that 4.3 caused. But was wondering if it's best to factory reset after each and every update on Android devices)
2. I know you said that sometimes reverting back to a previous firmware isn't always possible, but can't using Odin with the correct firmware version work? Like Goldie mentioned in the above reply. And does changing the firmware via Odin require rooting the phone?