The most puzzling thing about iPhones is the odd variations in problems people have. exact same phones with same OS versions behaving differently. One is dropping calls when you turn the screen off and the other one is fine. Mine screws up playing mp3's over BT and no else can replicate. I have lag and you don't, etc. This type of behavior you see on PCs, due to the wide variation in hardware. iPhones shouldn't really have these problems. As Apple spreads their lineup further, I fear problems will only worsen.
Smartphones are still kind of new, but I don't cut them much slack for it. It's a computer with the same components. You have a cpu, ram, mass storage, screen and OS. Yes its way smaller, but miniaturization isn't something new to the electronic industry. I think the problem resides within the OS itself. along with flash memory as storage. Smartphone OS's probably don't have the same level of resiliency that modern desktop OS's have. I also think that flash memory is prone to corruption, especially when the OS has no safeguards against bit rot.
Of course I have no idea what I'm talking about, so this might all be BS