Users surely noticed, but Heroku definitely noticed before my users did. They're quietly working on a solution and I can quietly go about my day. If my users start complaining, I'll have time to talk to them; time I wouldn't have if I was neck deep in log spew.
Having run apps on my own servers before, I know what a pain in the ass it is to deal with downtime yourself. I'm not particularly good at it, so I appreciate having experts take care of it for me.