I canceled around December and it was shockingly easy. Just a few clicks and it was done. It even gave me a prorated refund for nearly the full amount of the cost of renewal (I forgot to turn off autorenew and it had been a couple weeks after the renewal). It was actually the easiest cancellation experience I've ever had.

I kind of wonder if they have an algorithm to check your purchase history and if you've given Amazon enough profit over the years (which I certainly have with over 23 years of purchases and at least 15 years of prime) then it just makes the cancellation a piece of cake.