I cancelled in May with their chatbox and not only was it hassle-free but instead of refunding the remaining pro rata portion of the year I got the entire year's subscription fee refunded without even asking for it.
Ahh, okay, glad to see they've updated the process. Previously you had to call and find your way through a maze of disinterested people putting you on hold.
I cancelled through the “sound very angry and know what charge back means” when I wrote to their customer service. That was years ago. I would likely resub when I can do so through Apple Store.
I still receive (paper!) letters semi regularly about subscribing after I cancelled. It was so hard to do too, cancelling my NYT subscription was a breeze in comparison.