Yes there are some occasions where it doesn't work well (when you're trying to unlock the phone without looking at it properly) but there are also many occasions where it works much better. Most of the time my phone now unlocks so smoothly that I don't even realise it was locked. I just take it out of my pocket, swipe up and I'm on my home screen.
Agreed on reachability though, that has never worked well for me either. I just avoid using it now.