I like the sound of much of this - especially the return of custom domains (a key reason a lot of people switched to Medium that was bizarrely abandoned), and the ability to import an existing newsletter's subscribers into your Medium one.
I still have major concerns about the new look to Medium publications, as none of those that have switched over have any sign of a navigation bar. It's just a long stream of blog-style articles. This is a serious backwards steps for readers, in allowing them to find specific types of writing within a publication. It's actually make-or-break stuff, as why one earth would ANY publication only make it possible for their readers to see newest-to-oldest content? It would take people hours to scroll back.
It's actually such a dumb change I'd be bewildered if it doesn't get fixed, because you can't expect publications/websites to look like they're a Twitter stream.