Alright, I'm gonna lay this down nice and simple.
- I like the redesigned red line for new messages. It needs have thicker padding above and below it however.
- I like the UI for more options under messages. This right here is really nice.
- I like the ability to see what time each individual message was sent at, versus seeing the time a message chunk began.
- PUT THE LINES BACK! It is so clunky and unorganized to remove the separation between messages. Gives me a headache to look at.
- Stop highlighting messages when I mouse over them. That is extremely distracting and unnecessary.
- Line up the reactions and more options button with the first line of the message text, instead of floating it slightly above. It's easy to move your mouse to, and then end up on a different message on accident. Inconvenient as can be.
- The reactions bar needs to go. Very rarely does anyone use the reactions (though they can be useful). If I want to use reactions, I'll be glad to click the subtle little smile icon next to more options.
- And please, put the line above the message bar back. It's all I have in this world.
I know you guys are receiving a lot of direct hate, and not much functional feedback. I hope this helped clear it up in a more efficient manner, so the next update can make everyone feel much happier with the UI!
EDIT: Here is my mockup of what the UI should look like. Cleaner, but utilizes the new features and designs. Please consider using something similar to this. Re-addition of the lines, the removal of most used emoji for reactions, centering the message options menu, kept the timestamp, and kept the red "new messages" line with extra padding.