I have been amazed by Face id so far. I used it this morning with half of the duvet covering my chin and my gar messed up and it still unlocked lol I did notice that sometimes when i tap to wake the lock icon shakes as though it did not recognise me but upon swiping up, its unlocked
Im finding Face id to be on par with touch id too in terms of speed. I have read lots of reviews about it being slow but that has not been my experience! I pretty much just tap my display and immediately swipe up and its unlocked. There is zero delay