Their UI, at least on Roku, is terrible. This makes the experience just poor. I used to purchase movies and TV shows via Amazon but the UI is so bad that it makes it not worth it. For example, I purchased Macross 2. It is unavailable for purchase now. I still have it but I have to scroll through everything to find it (search does not work). You cannot even organize your purchases alphabetically.
I barely use Prime Video any longer because of it. Paying a monthly fee for a service that has maybe 1-2 watchable shows is just not worth it.