This isn't a fair example, but I have an older model iPhone that I got free (I use the Nexus One I bought unlocked from google) and I've done the jailbreak and unlocked it and everything. Just playing around with it.
In Cydia, the jailbreak app store, if you go to search for an app you're stuck there if you don't want to search. You have to press search to get out of it, or the home button. Usually if you select a text box in other apps, there's a button at the top to exit the keyboard.
As I said, it isn't a fair example because official (or app store approved) apps are supposed to behave consistently... but they don't always. It's been a while since I regularly used my old iPod touch (which I gave away after I got the Nexus One), so I can't give you any specific examples but I found the little inconsistencies in apps incredibly frustrating, because often the only way to get out of something or just go back would be to hit the home button and restart the app.
I do agree that the inconsistency in how the back button behaves in Android can be confusing, but I much, much, much prefer having it (and the other buttons) over the iPhone approach.
When the apps you use all do the UI right, and consistently, I do think iOS does it better - a lot slicker, anyway. It's just that in reality, with the types of apps slashdot readers are likely to use, it doesn't work very well a lot of the time, and Android is superior in handling inconsistencies.