I'm with Tom. (Not literally), this is huge although I can see why some of you think it's meh.
I've been quite vocal about how poor I felt certain parts of iOS were compared to Android, bits which should be in it were conspicuously missing. They've had widgets for a couple of releases, but provided no API to make use of it. Widgets are a killer feature on Android, you might not think you need them/want them but once you start using them on iOS you'll wonder how you ever managed without them.
Third party keyboards are huge as well, if you've ever used a decent third party keyboard on Android then again, you'll know just how good they can be. I hate using iOS7 because of the horrific UI mistake that is Caps, why on earth they don't reflect the caps key in the actual letters is just odd, but at least in 8 you'll have to choice of keyboard.
My only real iOS gripe that remains is the lack of an app draw, the home screen should be where I stick my apps from the drawer, the drawer should show them all, this way all the crap built in apps that I don't like/use/want can be hidden.
The extension apis are huge as well, this is another killer feature of Android that is sorely missing on iOS. Now you will see apps making use of other app features.
I fully expected Apple to carry on with their head in the sand ignoring basic functionality gaps with their "We'll do it our way" approach, but they've decided to follow a different approach now. Maybe now we're seeing the fruits of Scott Forstalls departure.
I've been on a Nexus for nearly 2 years because I felt iOS lagged badly, I suspect (if the bigger screen makes an appearance) I'll be back under iOS.