The new top bar has been deployed on Meta Stack Exchange. I have to admit, I'm not a fan.
To give more specific feedback, I really don't like how the Stack Exchange logo to the very left of the top bar has been made useless. On the old top bar, I could click the logo and get a dropdown of my most visited sites. On the new top bar, I click on the logo and get taken to the Stack Exchange homepage at stackexchange.com, which I never use. (Hot network questions are a complete waste of time, and the Stack Exchange homepage doesn't have anything else that would mean I would want to visit it regularly).
I don't mind the Stack Exchange logo being in the top bar, but if it's going to be there, why not make it do something useful? Right now, something that does something useless is being placed in a position that makes it extremely likely that it will be clicked. The dropdown that shows my most visited sites is on the right, which makes it hard to see and makes it less likely that I'm going to use it. I would prefer if that was moved to the left.
Apparently a dev made a change minutes after this was posted and the logo now does nothing. I'm also not a big fan of the logo doing nothing. It's a waste of space, it's confusing because everything else in the top bar is clickable, etc.