There is no application I've never heard anyone, other than a Gruber/Scoble like geek saying, "I need to buy an iPhone because of this app". In fact, ask someone who does NOT own an iPhone to name one iPhone application. Just one. Any one will do. I bet most of the time the answer will be a blank stare. If you're lucky you might get "there's Facebook, right?". And maybe if they're a gamer you'll get "Angry Birds" or "Doodle Jump".
The notion of a killer app for phones is a dead notion. People have a need for phones first. Then they decide which one to get. They are NOT looking at apps and deciding that since app X is on iOS that they'll buy a smartphone or an iPhone.
I used to want to replace/modify/customize my personal user experience, and now that I'm older, I prefer the more closed model that Apple provides because frankly, I just don't care about spending time on those things any more.
The N95 was out for a year earlier and had a mobile webkit browser and 3G. That said, the 2G iPhone had a larger screen.
When I say that there wasn't a competitor that was close I mean in total experience not just having the web. In my opinion all the little things matter immensely.
Really? Halo was well marketed by Microsoft as a leader game that ran on Xbox, but it was fairly average as an FPS - do you have a ref for this?
Of course, the Xbox has since died and we get along just fine with a PS3.