Like what? Yes there have been some enhancements but the fundamental UI vocabulary and representation is the same. iOS was a big leap forward from the alternatives in 2007. Nothing we've seen since has been even close to as radical.
I find it really fundamental to swipe left and right to change the foregrounded app, and have the other apps still there where I left them when I swipe back. That's a huge huge change, and takes it from toy to tool.
Agree that notifications pull down and similar are gravy, but tasty gravy nonetheless.
Like I said, no fundamental changes.