Was in a shop today,
Tried: Galaxy S, HTC Desire HD, Nokia C7, Samsung Omnia 7 and the iPhone 4.
Simply, they all suck compared to the iPhone.
None of them offer a UI that is as consistent and feels as unified at the iOS.
Galaxy S and Desire HD with their powerful processors and GPUs are still totally laggy, jittery and slow, made me wonder, what's the point of all those dual core CPUs, huge RAMs and powerful graphics chips when Android is simply not ready to take advantage of any of that? There is no hardware acceleration, and it tells.
Then there is the UI, edge bounce effects are present in some applications and menus, absent in others, some applications look native, some look like they came from a different phone, there is no consistency at all, in the iPhone everything is consistent, if something pops up, even insignificant, and you scroll up and down there is bounce effect, everything looks "integrated" and native, all that is simply absent in Android.
iPhone's and iOS's touch detection and keyboards are also much better.
Nokia C7 and Symbian feels like I'm in some cold Siberian nuclear bunker using a command line terminal, it's in a MAJOR need for a UI overhaul. Problems when scrolling with it registering your taps and opening up whatever, annoying. Although, it's menus did feel a bit smoother than the Android, the homescreen has a lag after you swipe, supposed to be fixed in an update.
WP7, meh... I didn't dig the UI, too all over the place, too square and monotone, although the UI is more consistent than Android and Symbian, there are bounce effects however they are limited, you get the bending effect but then run in to a "wall". Overall just not impressed by it at all.
Apple are just incredible to create such an amazing platform with nothing to reference or copy, incredible.
Before you call me biased, I'd like to note that I don't own any of the above listed devices, nor I have a frequent interaction with any of them.