The iPhone sold like crap when it was launched.
Well, that could have something to do with the fact that it was only available in the USA and even there it was AT&T only - at a time when the USA probably wasn't leading the world in cellphone adoption. ISTR at the time things like text messaging were vastly more popular in the EU & UK than in the US.
Oh, BTW, I did have a pre-iPhone smartphone (HTC WinPhone thing with slide-out keyboard). Yes, they existed. Yes, they were crap - mainly because the UI was a train wreck that tried to combine keyboard, number pad, jog wheel, joystick. touchscreen, stylus etc. and didn't do any of them particularly well. The iPhone completely revolutionised the UI by choosing one mode - touchscreen - and doing it really well.
Now, I never got an iPhone (didn't make enough calls at the time) - I got an iPod Touch and, later, an Android phone, mainly because I wanted to try both iOS and Android... iOS won hands down on polish and ease of use.... Android won hands down on cheaper phones, expandable storage and replaceable batteries (had an extended battery/back for my first Android phone - appreciated it when I got stuck in hospital & it lasted for several days until I got someone to bring in a charger...)
However, I was pretty convinced that iOS was better, and I was going to switch to iPhone when the iPhone 5 came out.
...then the iPhone 5 actually came out.
...then Apple castrated their Maps application (it may be OK now, but initially it was pathetic & it was a while before Google released their own iOS Maps app).
...then I saw the Samsung Galaxy Note 2

Wow, a screen big enough to
really use the internet, a "proper" stylus (with hindsight not sure that was sucg a big deal) expandable storage and replaceable batteries (although, turns out that the standard battery had stupendous battery life... but at least the option was there).
The thing about the iPhone 5 is that the tall, skinny screen was perfect if your #1 priority was phone & one-handed texting - but not so good if, like me (and many others who took the Android phablet route), your priority was web, email, maps, apps, media with occasional phone & text way down the list.
Apple came to the large screen party a year too late and
then decided to only offer a choice of "large" or "humungous" (or last year's model warmed over) - annoying all the people who
did like the 5 - instead of "best for phone & text" and "best for internet".