I not only cancelled my Prime subscription last year, but I also bugged the hell out of Amazon customer support until they refunded me for the entire year as well. Word of warning; they classify really inane things as a "use" of your Prime service. 1 Amazon Music MP3 play == 1 parcel delivered. They have a limit of how many times you can "use" your service and still be refunded. I did eventually get a full refund, however.
Prime was great when it launched here in the UK, now it's so unreliable in many places that it's completely worthless. The primary reason I used it (and I used it from the very first day) was for the 1-day postage. I think it's 2 days in the US, but frankly our country is pretty tiny so it's not exactly optimistic to do 1 day delivery when the Royal Mail can get me a parcel at 9am in South Wales that was posted at 5pm in the Scottish Highlands the day before.
I had a single parcel delivered on time in the past year, all the rest would be at least a day late. I live on what is essentially a ring-road of Cardiff, and it's insanely easy to deliver to me. There's one of the older Amazon depots within about 45 minutes of my flat, and I think a new one over near Bristol now.
My apartment block has banned Amazon's couriers from leaving parcels with the concierge, because they would rock up, pretend to deliver parcels/eat their lunch, then dump 30 parcels in the concierge office. So now they just dump them outside doors, indicating when you aren't home. They can't even deliver to the Amazon Lockers nearby within the delivery window, and the lockers are nearly always full because we have so few other options.
I've spent the past few months actively seeking to purchase everything via alternative vendors in the UK, and overall, I don't miss Amazon in the slightest. Although eBuyer also sucks (no weekend customer services, wut).
I'm so glad Waterstones is back on form here too; it feels quite poetic to ditch Amazon for its original purpose as a bookstore. Good riddance to them.