This is what i just submitted via the fancy new feedback window. Copy and share if you like:
Hi!
Since you're making the "new channels design" mandatory next month, i'd just like to make the following observation: I do not see one single thing in the "new channels design" that improves or enhances my user experience.
Not. One. Single. Thing.
If I were to suggest any improvements, it would be the option to completely emulate the "OLD" channels design.