I have a 6S from the original batch with the bad batteries. I never had it replaced because it worked fine (a coworker's most certainly did not), and it made a good excuse for a free replacement later down the line.

Now that it's finally acting up, I'm in waitlist hell because of the advent of the battery replacement program. I've been on the wait list for our local repair shop for about a month now, it's pretty crazy. They said they've had hundreds of people sign up.