When it works fast, face unlock can be rather stunning. Occasionally it would catch a glimpse of my face obliquely and unlock before I even got to position it correctly.

However like others, I turned it off because the performance was highly variable, and the failure mode consists of a many-seconds wait which can be extremely infuriating (even embarrassing, as as you stare blankly at your phone for 5 seconds at a party, trying to quickly get someone's number or something).