1) Apple was first-to-market. And I don't mean the iPhone. The iPod was when apple just used a rocket booster to jump ahead of the game, and finally their steam is running low.
- The iPod was revolutionary. - The iPod was never quite cloned "correctly" there was more to the iPod than meets the eye. By the time Apple removed the DRM restrictions it was too late for consumers, Apple had already made a dent in the market which others could not recover from. - When everyone finally caught up to the iPod... poof there goes the iPhone again darting apple ahead of the game. For at least 2 years before again anyone even came close. - The iPad is another attempt to do the same, but by now it did not dart them as far as the iPhone did. The competition is now riding on unicorns and are hard to out-meneuver.
2) Apple literally filled the void of the tech industry. The void was in usability. It was simple, give users a very friendly UI, and lets do away with core concepts we find important but most don't. I don't know how to explain "files" to my grandfather. He asks me "will my programs be there when I leave home with my laptop?" I tell him yes and no. You need an internet connection because to him his "programs" are the websites he visits. He can't even grasp the concept of moving files from hard disk to usb flash drive. To him "files" are mythical unicorns. And I see this from many people, he is just the best example. Apple is trying to cater to the audience of people who are completely lost with computers by making computers behave like "real" objects are inside them. The ipad is a great example because it makes things tangible. A child can understand it.
The point at the end is this: Apple never had "features" they had "usability". OSX is a great OS because it combines user friendliness with unix. That is why developers love it. Hey I can't get over how awesome it is that uninstalling an application is dragging it from applications to trash (just got a mac). And to top it all off its quite easy to find all configurations and such for any installed application. On top of it all I don't feel like I need to re-install mac osx every 6 months like I had to with windows xp. AND to make it even better their keyboard shortcuts are a perfect fit for a laptop keyboard without having to resort to a lack of home/end/page up/page down keys. I swear check out those 4 frequently used keys layout in ANY pc laptop. It is insanity. Look at mac, the defaults are made so that you can use the say layout/combinations everywhere, brilliant!
In the end apple is running out of steam. I think they will level out in a year or two taking their place as the new Microsoft of the industry (which is fine). I just wish macs were not so f-ing expensive. I mean I feel like I am getting inappropriately touched by Steve Jobs every time I add more ram to my order.