I only speak for me when I say this, but it seems to me that Apple tends to introduce things that will either be used or not used (like Passbook), whereas Samsung introduces all of these cutting edge new features like Smart Stay and eye scrolling (rumour at this point); things that just about everybody can and will use, as long as it works well.
I criticise it because it's something I would definitely use so long as it works. If an accidental flicker of the eye or a misread glance is going to completely scroll the page from where you're reading, then the feature is a failure. It has to work well otherwise it's going to be an annoyance. Nobody is going to say "oh wow, great, wonderful" if it's going to be more annoying than the current scrolling system.
I can't think of any UI enhancements that Apple has made where you would have to worry about wrong or misinterpreted input from the user, but Samsung is bringing in these kinds of features all the time, and it needs to work well.
So far, I think they've done a great job with making the gestures and Smart Stay very reliable, and I'm sure the eye scrolling will be great too; it doesn't stop me wondering what will happen when you look at your phone in the dark, or if you accidentally glance at a scrolling hotspot, or if it thinks you've glanced at a scrolling hotspot but you actually haven't.
Edit:
Also, the guy that got shot down in flames earlier in the thread for commenting on battery life has a valid point by the way. Smart Stay only uses the front facing camera very briefly every time the screen is about to time out, but this would need the front camera on all the time, unless it's only going to check every so often, but then there will be a delay between when your eyes get to the bottom of the page and when it scrolls.