One word : Gestures.

We can think of things like slide to unlock but much more importantly scrolling. If something shows more the mastery of the iphone UX of that time it is definitely scrolling, who categories it as gesture now? It's completely normalized, on all other Platform of that time, you had to play with arrows and the scroll bar. Now every platform has it.

Ah very good. Yes, I agree. Simple things like a scroll bar in a browser window right? I remember how difficult it was to tap that small little icon on the lower right corner of the screen. They simple copied mouse behavior onto the phones. And Apple that this out from a 0-level perspective. Thanks for the insight!

Using a touchscreen pre-iPhone usually felt like executing commands on a computer application.

Using an iPhone felt like directly manipulating the underlying content. It was a qualitatively different experience that only superficially resembled previous touchscreen devices insofar as it used similar input hardware.

Note that Apple didn't invent the concept of a responsive UI thread with physics-based UI metaphors, for example Jeff Han demonstrated a fairly sophisticated example at TED2006[1] the year before. But to my knowledge the iPhone was the first mass-produced device with a direct manipulation interface.

[1] https://www.ted.com/talks/jeff_han_the_radical_promise_of_th...

Maybe. But the author says speed IS the killer feature (for products) so it has to be true at the higher level too. UX is the perception of the user of the product and their, well, experience using the product. If it's generic it's because it really is that generic, because users won't know why exactly they like a product.

But in the case of iOS vs Symbian:

- as others said: capacitive touch screen (this is not an OS issue, but iphone was among the firsts to use it, definitely earlier than Nokia). This is huge. Like the thing that everyone was talking about (around me) when the original iphone came out is how you could swipe to see the pictures. And it wasn't just for paging, it defined how you could interact with the phone (think pinch zooming, and rotation - not sure when these were added).

- the touch screen UI itself. Nokia played around with the touch UI before, but never really liked it. It was expressed several times internally, that touch is just a no go. But no wonder: the resistive touch screen is pretty bad, but also Symbian itself was built on the assumption that all you have is keys while iOS was built with touch UI in mind from the very beginning. (Now, of course touch was added to Symbian, but that's just not the same. Or they didn't put in the effort. Nokia even had an experimental touch phone released to the market in 2003, the 7700[1], but it was mostly ridiculous.)

- the UI just was a lot more polished, looked better, classier, the graphics was better. They had OpenGL and probably a graphics accelerator - nothing like that in Symbian, of course. (It even took the android guys by surprise, I remember reading/hearing in an interview that when they saw a demo or the release, they've realized that they had to redo the UI from scratch. Because before that they had this Blackberry-ish/Symbianish idea, they thought they were competing with that.)

- I'm pretty sure it had a better browser.

And this pretty much defines the experience, the feel a user gets from the phone. It couldn't send or receive MMS-es (some people may have used it then, but most I guess just wanted to have the feature), it couldn't receive 'push' email. I.e. you had to manually refresh your inbox, emails didn't just arrive. It didn't even have apps. Symbian had all these. It has had these for years then. It even had an app store like thing (at least you had to send in your app for verification which would then be signed by Nokia or it couldn't be installed - that was a new thing around 2004-2006, something I think nobody really did before).

[1] https://www.gsmarena.com/nokia_7700-570.php

My follow up question would be: Would a capacitive touch screen with 0.5s latency have made this the killer feature? Or did the capacitive touch screen enable high speed input?

I'd argue the latter, but it could be a question of framing?

I don't know. Again: I think the killer feature was the whole UX. Slow response times is definitely disturbing. (All my android phones got into this state sometimes.) You just don't get that feeling, but it couldn't possible happen to iphone because the the UX was the center of the whole product. I'm not an apple fan (never had an iphone, and the early ones kept pissing me off when friends asked for help) but it's obvious that they are obsessed about UX and polishing the UI.

But you are right that the capacitive display itself makes the interaction faster because it's enough to touch while the resistive has to be pressed. So it's probably slower and feels like you have to put in more effort.

I'd say based on the number of friends I have who use old or cheap Android phones with terrible latency, it really was the touch screen and UI/UX that played the main role.

Sure, for many, iPhones are still preferred because of the low latency, so it matters, but I suspect the iPhone would've done just as well if the latency was bad. The competition was about finger vs keys/pencil, not latency.

Thanks for the details. I remember the capacitive screens. They were awful! :)

Well, capacitive is what we have today. The old ones, that you actually had to push (and not just touch) were resistive :)

I meant those!