On my favourite site, a new design was announced. It contained a lot of links to posts which in turn contain a lot of links, answers, timelines, and references to stuff like Teams which is not relevant to me. So, I am pretty overwhelmed and confused. I am therefore asking for a summary of what I need to know for understanding, evaluating, and criticising the design for proposed for my site, specifically:
What major changes can I expect when switching to the new theme?
What is the rationale behind the change as a whole as well as the major or controversial changes? What is this responsive design everybody is talking about?
What are the restrictions of the new unified theme?
What parts are still customisable for each site?
What are the most common suggestions and what is their current state (rejected, in progress)? I am asking this, so I can avoid redundant worries and criticism.
This is intended as a FAQ to be posted as a reference in the individual design announcements instead of the convoluted general announcements, requests for comments, and similar. It should be mainly self-contained and only contain links for further reading and reference. Please make answering this a collaborative effort. Also feel free to improve the question.