Last night I quoted Marco Armant asking if Android phones would ever achieve iPhone-level polish and usability and a lot of Android enthusiasts fired back that they could do things on Android that they couldn't do on iPhone, so Android was more usable.
That's not usability, that's functionality. Those two can be as diametrically opposed as simplicity and complexity...
Copy and paste on iPhone is broadly consistent system-wide. On Android, even Gingerbread, there are at least three or four different ways of doing copy and paste in different apps, including Google's own Gmail. They're both functional but iPhone is more usable. FaceTime on iPhone 4 is locked to Wi-Fi but works the same way as placing a phone call. Android (and before them, Nokia) devices had front-facing cameras first but relied on 3rd party apps to handle the video call, even over 3G, but with decidedly mixed results. Android is more functional, iPhone is more usable.
I've mentioned other things before as well. Memory management on iPhone is invisible to the end user, they're never supposed to see an "out of memory" error. Multitasking on iPhone, via the Fast App Switcher, is all but invisible as well unless you hit the Home Button twice in rapid succession. It's literally behind the scenes and can be easily ignored. The App Store, thanks to iTunes, just works in over 90 countries around the world, even though it doesn't have some categories of programs, and doesn't allow for themes and skins. All of those might prove less functional to a hardcore user but it's more usable to the mainstream majority.
Even notifications on iPhone, one of the nastiest thorns iOS users still have to deal with and something most of us are begging Apple to fix in iOS 5, are so singular and modal as to be extremely usable (you just click and they go away or you go to the app) to a non-tech savvy user. (Something a few very well known, very push-notification heavy app developers have said they fear losing if Apple goes to a more Android- or webOS-style notification system).
A stock iPhone is inarguably far less functional than a high end Android device, but its consistency, attention to interface and experience detail, and level of fit and finish make it just as inarguably more usable.
My 2 year old godson can use iPhone well. He can turn it on. He can find and launch his apps. He can play his games and read along with Dr. Seuss and Disney. About all my 2 year old can do with my Android 2.1 Nexus One is throw it.
That doesn't indicate the iPhone is a "toy" for children, it indicates the level of usability Apple has achieved, and is something Android enthusiasts should be angry that Google doesn't seem intent on matching, just as iOS users are upset when they see that cool new feature Apple seemingly has no interest in.
And yes, you can Jailbreak an iPhone to make it far more functional but that increases complexity and lowers usability, bringing it more in line with the Android model. (I'm currently Jailbroken via redsn0w, though ironically my Nexus One isn't rooted. Go figure.)
None of this takes into account Apple's industry leading accessibility features either, which make iPhone usable to those with low or no vision. Nor does it reflect how carriers often mutilate Android by locking it down, or locking out or stripping functionality entirely. (Even Google with 720p video recording on the Nexus S.)
So if experts want to argue Android is more functional than iPhone, go ahead. Nokia enthusiasts can argue the same and probably from way before Android came around. However, since the day it was released in 2007 nothing is yet as usable for as many people as iPhone.