Probably because it's a really great OS, with features that iOS users can only dream of, like wireless charging and NFC.
Just a guess...
I'm not an iOS user....(well I use an iPad) but really how is this phone any better than the gs3 ( hitch I had, but now have a htc one).
Wireless charging is still a gimmick in many ways, and NFC is basically on every new android phone ( for the past year or two).
But at the moment android just pisses all over windows OS.
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Right, because so many people use NFC right? No one and I mean NO one aside from hardcore tech nerds have the slightest clue what NFC is much less actually use it
I actually think NFC is an awesome feature, but just hasn't caught on due to marketing and companies not willing to spend dosh to join on board.
When apple joins the wagon, it will catch on because market things in an awesome way to both consumers and companies, which will be good for android users as well.
I just bought a few nfc tags myself and they are awesome to use.
I have one near my front door called " going to work" which turns off wifi, puts power saving mode on, switching on my music etc all with a single tap of the NFC tag.
Then I have a sticker on my works computer which is called "at work" which switches on wifi, turns off music, puts my volume on a low setting etc all with a single tap as well. This is normally what I did anyway when I had an iPhone, but now I don't need to flick through settings and buttons, I just need to set it up once and then just tap. Awesome