Everyone's saying Apple is slowing, go ahead and buy the GS4 when it is released and see for yourself. The OS is not as polished, popovers and menus fly everywhere, the Back button takes you to places you don't intend to go to, and so on. Then maybe you will decide which OS is better.
Samsung has successfully garnered attention by painting Apple as the old and stagnant, and you seem to agree with that.
I had one for three weeks, and to be honest the only reason I did not keep it, was not for what you said, but for the fact that I am all Apple even my email account, so until I make my decision to switch my email account I am staying with my IP5. Unless you have owned an SGIII I would not take your comments as having any value simply because I never had an issue with the Back button, their OS is smooth and quick and the phone is just as good as the IP5 IMO.
I love Apple products, and I will never stray from the MBP simply because to me it is the best Notebook out there with the MBA as well. I will never use windows again, ever.
As for the phone, there are good and bad to each, but I think the iPhone's run as top phone is over, they need to start really coming up with a new design each year or they will lose more market share, long gone are the days of the 3GS, 4S, they need a whole new phone each year. Sure they will sell whatever they produce, but what magic number will make them realize people are getting tired of their basics.
I used to know a lot of people who went to the iPhone when Android stunk, but they have come a long way, and I am starting to see a reverse trend from people going from other phones to the iPhone, now it is people going to other phones from the iPhone, not something I am causing, just what people are doing.