Let’s start with the positives.
It looks excellent on mobile. Clean and to the point. No clutter.
But then it comes to show once again why “mobile first” approach often fails in one thing. It’s mobile first, not mobile only. To be honest, (and I’m echoing many other responses here), it’s looks horribly boring on desktop. + What Andreas Beer said: “Where’s the love?”
Or is this a push for us to create our own publication? Those at least still have some added visual flavour to them.
Then again, I’ll probably get used to this and won’t even notice the change anymore in a few weeks time. But I would still love you Medium folks if we could at least have some way of visually differentiate our profiles from everyone else’s.
Maybe hide the header in mobile but still show it on desktop? Or make it optional and leave it up to each of us to decide what works best for our taste? :)