I'll just say one thing:
Any input would be appreciated. (I found the Yahoo Mail app for Win8 at the "store.") But my popmail accounts . . . well, they're on the web, in several places, and sorta on Outlook 2010, and sorta not.
Related: how do I configure the new Windows calendar? When I send a mail with an appointment from my phone to "myself" and open the "invite" attachment, Outlook 2010 opens, not the new Windows calendar. (Nor is there a Yahoo calendar app, which is annoying, but that's not Windows' fault. Although it would be handy to have one from "the store.")
Windows has always been about openness to other software and hardware, and smooth interoperability. You're not trapped in an "ecosystem." But the mail and calendering is all messed up at present. This used to be what they were really good at: well, at least on Windows 7, they were. And even before, if you wanted another client, it all worked rather seamlessly; not now. What happened? (I know: Bill Gates is off immunizing the world, or something. Wish he'd go back to work.)