Basically just a more intuitive and polished overall user interface. There was definitely some learning time, but once I'd learned some of the common actions, I found it much simpler to work with. But it's probably something that is subjective, so I can't vouch that everyone will feel the same way (indeed, I have some friends who have switched from iOS to Android and found the latter more intuitive).

Of course, the price issue was a little different for me since I prefer not to replace devices often, so the longer software support actually means if I amortize the cost of the phone over the time that I use it, iPhones actually come out ahead of Android phones on price.