Everyone in this thread is arguing over pricing, subscription, privacy, etc., rightly so, I'm sure; and not one argument it seems on just how bad the new design is. I installed this on Windows (which I loved that they came out with a Windows client), and, for the life of me, I cannot figure out how to get my side-by-side view back (vertical list of email headers, then viewing the email to the right).
If you're going to try to force your userbase to pay, the least you can do is not screw up your design.
I guess I'll be finding yet another email client. And honestly, I would have probably paid for this had they not screwed with the design so much in the vein of "productivity".