For me, most of the changes are in the area of "Who thought that was a good idea???"
Perhaps these are all to 'optimize' things for folks that communicate with their phones??
'Owner knows best", I guess.
Short list after 5 minutes of use:
1)color palette choice Huh? Yuk! Orange + unreadable fuzzy pastels- what's the problem with black for font color? And, a non-migraine background and palette?
2)buttons in the reply window are all very very faint and fuzzy- definitely a step backward from what was before...lo-rez
3) 'Normal' reply window is gone - only 'Quick reply' shows when I click on 'Reply to thread'. To get the 'old Normal' reply window, I have to click on 'Go Advanced' and then the previous messages disappear from the page.
4)'Default' smiley collection has changed, and some of my old faves are gone completely
5)'Today's Posts' button has disappeared
6)Multiquote button doesn't deserve a text description, apparently
Carry on.......I'd insert the blue 'unhappy' smiley here but it has been removed........