It's about the new APIs and the added security. Those things matter in a huge way. And all of those features you mentioned, aside from Airdrop (which I'm sure they had a good reason for but don't let me stop armchair software engineers from arguing) are all impossible on the iPhone 4 because of hardware limitations.
Completely incorrect. Siri worked fine on the iPhone 4 BEFORE Apple bought Siri and castrated the iPhone 4, trying to force everyone to upgrade to the 4S. You see, Siri was the only 'new' thing to get people to buy the 4S. And I had an iPhone 4 at the time and after jailbreaking it, I used Siri just fine. Apple was utterly and completely full of sh#t about the 4 not being able to effectively use Siri. They lied. End of story.
Additionally, adding turn by turn navigation would not be an issue for the iPhone 4. Hell, even more limited hardware phones by Nokia (feature phones in fact!) can do it just fine.
As for Airdrop, Apple once again purposely neutered not just iPhones, but also Macs. 1 year old iMacs were left high and dry from being able to use Airdrop. Pure crap when you spend 2k on an iMac just a couple months earlier.
It's a 4 year old phone. 800MHz single core. Expecting it to power through some of those features is unrealistic. I'd rather have up to date APIs and security over the alternative of getting absolutely nothing and using an OS riddled with security holes (Galaxy Nexus for example, which has much better specs than the iPhone 4 yet already lost support. It's depressing being an Android user and knowing that the makers of your phone don't care about its customers).
You just killed your credibility. You have no idea what OEM's think, unless you are a CEO or board member of an OEM? As for security holes, I believe Apple is the only company to have its developer site hacked? Gotta wonder how many sleeper exploits were added? I have no idea if any were or were not added, but it is a valid concern that Apple has yet to publically address. They probably have no idea themselves and won't know until a virus or malware is activated. Security and malware effects all OS's. Even iOS and OSX. Get over it.
It is pretty obvious you just simply hate Android and love Apple. That's fine. Just say that. Don't try and blow smoke up our butts with b.s.
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iOS 7 multitasking is quite different than Androids - I assure you. While iOS 7 has it's bugs, I haven't found it to be any slower or less fluid than KitKat. My retina iPad mini, 5S and 5C all run very smoothly with the occasional bug. It'll be sorted out and 7.1 will be what iOS 7 should've (and likely was supposed to have) been.
I agree with your statement. I have the first gen Mini and iOS7 runs great. Can't find any flaws (other than a random force close, but you get that on Android too.) The iPhone 5S I just got for the wife does have the random reboot bug, which is being addressed in iOS7.1 update, so not concerned there.
Personally I find both KitKat on my flagship phones (HTC One and Nexus 5) run just as smooth as iOS7 on my iPad Mini and wife's iPhone 5S.
BTW, did you see my post about getting the 520 unlocked from AT&T? If you got your 520 from Microsoft, it won't be an issue. Just fill out the form on the link I gave out and email it in to AT&T. You will get an unlock code in roughly 2-3 days. My T-Mobile sim works great in my 520. And really easy to just call up and add minutes via a credit or debit card. Convenient.