iOS is so responsive and so liberal with animations that it has a very tactile feel, and rather than thinking “tap this button to open” or “swipe across this box to share”, conceptually, you just move the things on the screen with your fingers.
The distinction seems subtle, but it’s important. Every action on the Surface feels deliberate. It feels like you’re using a computer.
The standard gestures don’t help, requiring many in-from-the-edge swipes that not only aren’t discoverable but also frequently conflict with scrolling. My gestures often didn’t work, and it wasn’t clear whether there just wasn’t a hidden context menu at that moment or I just screwed up the swipe.
Most of the animations also aren’t helpful, with minimal spatial consistency. Many animations seem arbitrary, not hinting at anything behaviorally useful. Microsoft has applied animations and gestures in Windows 8 about as effectively as they applied color in Windows XP and transparency in Windows Vista: they knew that Apple had been successful with these features, so they made a checklist and just applied them haphazardly. “Apple does animations, so now we do animations! Apple does gestures, so now we have gestures!”