In reply to felt:
This is what it looks like now, before it used to be the blue+white layout, with folders down the side, etc. Even the cramped up smartphone version is superior.
You can't adjust the width of the "columns" to show more of the sender's ID or more of the email title - if you have the window as a full screen (or near to) then there's lots of wasted space whether you want it or not.
You can't just drag files into a new message as attachments, you have to select them via a file dialog box one at a time.
You can't see your folders all the time, only via a drop-down "menu".
I'm sure there are further negative improvements to be found but I'm minimising my time with it; haven't found any positive improvements.