But for actual live users who don't see anything but a transient screen, Anubis is a better experience than all those pesky CAPTCHAs (I am bored of trying to recognize bikes, pedestrian crossings, buses, hydrants).
The question is if this is the sweet spot, and I can't find anyone doing the comparative study (how many annoyed human visitors, how many humans stopped and, obviously, how many bots stopped).