I don't own an iPhone but my fiancee has one. Of all the generalisations in this thread saying that the UI experience is smoother on iOS is probably the only one that is true. It is also one aspect of the overall experience and other things can easily be more important and I will give a couple of examples:
1. An HTC Desire-Z. This is an Android phone with a slide out keyboard. Mine suffered from a bug whereby the phone would sometimes lock up. When it did this it would not wake up when you pushed the power button and, most importantly, would not respond to incoming calls. As I did use the phone as a phone and not just a personal organiser/media/internet device this was a serious failing because sometimes people would try to phone me and get voice mail even though I was available to talk. By comparison there have been several cases of Samsung devices randomly rebooting themselves and, while being completely stable without reboots would be preferable, auto rebooting is infinitely preferable to the hard lock up of the HTC because it gets the phone back on the network so it can be called.
2. An iPhone 5 which sometimes loses WiFi connectivity and will happy report that no WiFi networks are available even when other devices can see at least three. The significance of this is that the owner has chosen her data plan based on the phone using WIFi at home and mobile data when out and about so if the phone uses the mobile network at home because it won't connect to the WIFi this either runs up a large data bill or exhausts the bundled data allowance. The bug seems to be in iOS 6 as people are reporting the same with iPhone 4Ss and iPads that have upgraded.
You can say my opinion here is subjective but to me these are both much more serious than occasional lag and the odd crashing app and neither platform has come out smelling of roses.
Regarding the comment about Linux running servers that are very stable and don't tend to crash or need rebooting, yes Linux can be very reliable. On the other hand when you run it on recently developed hardware bugs in either the hardware or the drivers developed for that hardware can be a source of unreliability. As the hardware has been around for a while the bugs in the drivers get fixed and the driver writers even manage to work around some bugs in the hardware itself but this all takes time and mobile hardware changes so fast this process is less effective on phones than on server or desktop PCs.