A phone that truly defines the title Smartphone. I mean there are other phones in the market who have the users as the second or third priority and their product in the first.
With the iPhone there is never a situation of failure, time waste or doing unwanted things etc etc.
The stuff from other phones which I don’t want to hear or not interested to do is like - keep internal memory free, install process killers, reboot phone, format/insert/re insert/replace SD cards, provide email ID(repeatedly) to sync data, touch screen yet 3 to 4 buttons, install "battery doctors", finally assembled device where we fear the SD card, battery etc may be compromised, app failed to open/not responding force close it, open source apps that liberally delete all gallery images.
There is never such a situation with iPhone4 or 4s, keep the software updating and configure initially and it s good to go.
In your warranty days if you’ve got a problem in iPhone’s hardware or software, that cannot be restored, you get a new phone in a day or two literally, from any official apple store.
Unlike others who only sell in store but make you roam cities for days and end up with a service, worth a week time.
About the physical strength - I don’t have a count of how many times I dropped/slipped the phone from my hand and I haven’t encountered any damage yet other than few scratches.
Few people comment against the phone only because of the price, but the price is worth to make which things to work and which not to work.
Finally,
If you don’t have an iPhone, well you don’t have an iPhone.