Oneextrapixel.com has a list of things that WordPress developers will need to know about concerning WordPress 3.5. However, end users are able to pick up a few things as well, especially the part about settings changes. According to the site, the admin page dedicated to Privacy settings has disappeared. The options on that page have been moved to the Reading Settings area. Also for new installs, the ability to change the Character set has been hidden and will use UTF-8 by default. I think this makes total sense and would like to see similar option UI be removed in the future. Even though the UI will be hidden, you can still access the option via options.php. Going this route seems similar to how FireFox works. While there are things to configure, those who want access to everything can go into About:config.
Over the years, the saying has been, “Decisions, not options“. I wonder when options.php will be renamed to decisions.php.