I'm currently waiting for a package "guaranteed" before midday. I've had a couple of emails since then, the last pushing it back to "before 9pm". It's 9.25 now.
They've delivered stuff to the wrong place. They've said they knocked and nobody answered (I work from home, wife is on maternity).
And their vans are rentals.
All in all it feels unprofessional. It makes me questions not only the value of Prime but Amazon as a whole. I've started shopping around a lot more.