I had one moment when I logged on today and it didn't connect, but I hit "retry" and it was just fine
I suspect either the 'hackers' never planned on doing anything in the first place and were just posturing (and maybe hoping their threats in and of themselves would cause server issues because everyone's going to be logging on today checking), or Niantic figured out some of the server issues and were able to handle whatever attack may have been thrown at them (they have been remarkably stable the last few days, and the update was pretty closely timed with this 'threat').
Or the attack hasn't happened yet, but I mean, by this point, it's not really going to affect many people unless they continue it over the next few days. And considering the number of times servers were down for hours at a time since it was released anyway? Yeah, big deal. Not like we aren't used to it.