Some things to be aware of:
- Left Navigation is active on most pages (but can be collapsed into a menu by visiting your site preferences - [instructions here]).
- Responsive layout is active, which lets the site adjust as browser widths change - no side scrolling (some pages haven't been updated, yet, though). For now, if you prefer the scrolling, you can disable this by clicking the "disable responsiveness" link in the footer.
- Link underlining is active. In an effort to make links more visible, they are now being underlined.
The layout unification is also allowing us to more easily improve existing features like tag watching and develop new features that have long been requested like custom question lists, which is currently in testing. We'd love to get more features out to you all and that's easier when we spend more time working on the new features and less time squashing bugs they cause because we have 60+ very different site layouts.
This is addressed in a Meta Stack Exchange post if you want more detail.
As part of the Stack Exchange network, international sites will soon get the new theme as well with the only difference: we will not have testing period, so the theme will be available for everyone.
If you find any bugs and want to report them, please be sure that the bugs are posted as answers to this question. If you have general concerns, please leave feedback on the existing MSE post
Please feel free to post your international community feedback here!