I love receiving anal pleasure. From fingers & tongue, all the way up to being pounded with a strap-on. Not sure of my limit, probably a 2 inch diameter is my largest so far, and maybe 9-10 inches deep. Not into fisting.
All I can say is that it just feels good. It's a sensory stimulation like no other. A ribbed toy sliding in & out past the anal ring muscle turns my legs to jelly. I have to beg to stop because I can't handle anymore stimulation. It's not an explosive orgasm like when you ejaculate, it's more like waves of warm water flowing over you repeatedly, never stopping.
So I'd say learn the pleasure you ass can give. It's eye opening.