I have severe plantar fasciitis and there are very very few products that actually help the condition.  I own Birkentock Arizonas, which are better than walking barefeet but are heavy and slip off my feet.  So I always walk a certain way to make sure they don't come off and that causes pains in other parts of the feet.  I ordered Reef Fanning's based on the reviews (obviously), to only wear around the carpeted house.  I wore them for 1 week and there was a sudden increase in pain in my heels and now knees.  I never had knee pain before.  The slippers seem to have fair arch support but the heels are not hollowed to provide cushion (a must).  This could very well be how my feet are structurally and not a design issue.  Remember the Fannings are not marketed as slippers for Plantar Fasciitis slippers, they only claim to provide arch support- which it does failry decently.  The slippers otherwise are well-made and look very cool.

-Orthoheel-
I returned the Fannings and got Orthoheel Waves, they were uncomfortable the first day and the strap still hurts between the toes and fingers.  But they are otherwise comfortable, after a week of wearing them I feel it is safe to keep them and transition over from my Birkenstock Arizonas (which have a great foot bed btw).