The iPhone is not unique in its featureset. Lots of phones have about the same, some even better specs.
Where the iPhone still stands out is the user experience and second that it is the only non-disposable phone.
Just like Macs, iPhones seem to be designed for longevity. Even the first gen iPhone can enjoy most of the OS3.x features. Look at HTC and other brands, they keep pumping out new models every 4-6 months or so. Making the previous models redundant, even the support is minimal.
Unlike Apple, those brands regard mobile devices as disposable items, so they do not even try to get users tied into their system.
Some say this is freedom for the user, but I think it is missing the point.
With respect to user experience, I don't think an open system will work. Look at Linux, very open, lots of choices, but none of them is any good from a user experience point of view.
Instead of thinking "what feature can this thing do", companies should rather have the "what feature does the user want to use" viewpoint.
Apple got it. After 1.5 yrs with my iPhone I still don't have the urge to buy a new phone. With all my Nokias and Sony Ericssons I wanted a new one after a month.
Yup, I'm locked into the Apple world. But I like it :-)