they are still doing well however they could be doing better had they gotten rid of Forstall earlier because iOS software is what is holding them back in most people's opinion. Spending too much time on paper shredding animations and not enough time on real functionality. I love iOS but it takes a lot of heat. Fortunately Apple has one really huge thing which is people in China love the products and they are still not on the largest mobile carrier in the country. iPhone 5S could be a success if all they changed was the radio to access that one network
The problem with China - it's poised on the cliff of a major recession. Apple is pinning its future growth on the Chinese market, but if they go into a recession those plans will likely not pan out.
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18 months? Why stop there? The iPhone 4 had a bad antenna problem and the proximity sensor had issues. iPad? That was just a big iPod touch nothing there. iPhone 3GS? it was just an iPhone 3G that was a little faster. iPhone 3G? It was just an original iPhone with 3G. Original iPhone? Who cares it didn't even have a physical keyboard. Apple will never sell any of those!
Just saying if you want to talk about nothing new, then you're just doing the same whining that has been done for many many years with Apple, much less 18 months. If Apple's 2012 sales are from products that "no longer excite" then bring on the boring, it makes billions.
Except when all of the things occurred that you mention, there were no real viable alternatives and Android was just getting its legs. In the last two years, Samsung has almost single handedly turned the Android ship into a successful endeavor and has become Apples #1 competitor. Who would have thought two years ago that what Apple had to fear was Samsung, not Google...
Today there is viable competition with a general public perception that Android offers more features than the iOS counterparts. I'm seeing more and more Android tablets in use, which is not good news for the iPad. So your argument works in a world without competitors, but that is not the world we live in today.